ISOLDE/ParmEd: UnboundLocalError: local variable 'compiler_package' referenced before assignment

[chimerax-bug-report@…]

The following bug report has been submitted:
Platform:        Windows-10-10.0.18362
ChimeraX Version: 1.1 (2020-09-09 22:22:27 UTC)
Description
UnboundLocalError: local variable 'compiler_package' referenced before assignment

UnboundLocalError: local variable 'compiler_package' referenced before assignment

File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-packages\chimerax\isolde\parmed\__init__.py", line 52, in install_parmed
'Please install {} and try again. \n\n{}'.format(compiler_package,

See log for complete Python traceback.


Log:
UCSF ChimeraX version: 1.1 (2020-09-09)  
© 2016-2020 Regents of the University of California. All rights reserved.  

> open "D:\Dropbox (NYU Langone
> Health)\LabIgor\Structural\yeastDot1More\SupplementPAPER\Building_010820\Isolde012320\Isolde012320.cxs"
> format session

restore_snapshot for "RotamerRestraintMgr" returned None  

restore_snapshot for "RotamerRestraintMgr" returned None  

Log from Sat Jan 23 20:35:08 2021UCSF ChimeraX version: 1.1 (2020-09-09)  
© 2016-2020 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> toolshed show

Downloading bundle ChimeraX_Clipper-0.15.0-cp37-cp37m-win_amd64.whl  
Traceback (most recent call last):  
File "C:\Program Files\ChimeraX 1.1\bin\lib\site-
packages\chimerax\help_viewer\tool.py", line 389, in download_finished  
session=self.session)  
File "C:\Program Files\ChimeraX 1.1\bin\lib\site-
packages\chimerax\core\toolshed\\__init__.py", line 903, in install_bundle  
_install_bundle(self, bundle, logger, per_user=per_user, reinstall=reinstall,
session=session, no_deps=no_deps)  
File "C:\Program Files\ChimeraX 1.1\bin\lib\site-
packages\chimerax\toolshed_utils\\__init__.py", line 213, in _install_bundle  
raise ToolshedInstalledError("bundle %r already installed" % bundle.name)  
AttributeError: 'str' object has no attribute 'name'  
  
AttributeError: 'str' object has no attribute 'name'  
  
File "C:\Program Files\ChimeraX 1.1\bin\lib\site-
packages\chimerax\toolshed_utils\\__init__.py", line 213, in _install_bundle  
raise ToolshedInstalledError("bundle %r already installed" % bundle.name)  
  
See log for complete Python traceback.  
  

> open "D:\Dropbox (NYU Langone
> Health)\LabIgor\Structural\yeastDot1More\Maps\maps_Aceto\1stProcesing\cryosparc_P45_J85_007_volume_map_sharp_local.mrc"
> format mrc

Opened cryosparc_P45_J85_007_volume_map_sharp_local.mrc, grid size
300,300,300, pixel 1.03, shown at level 0.334, step 2, values float32  

> open "D:/Dropbox (NYU Langone
> Health)/LabIgor/Structural/yeastDot1More/SupplementPAPER/PDB/a_Aceto_PDB/Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb"

Summary of feedback from opening D:/Dropbox (NYU Langone
Health)/LabIgor/Structural/yeastDot1More/SupplementPAPER/PDB/a_Aceto_PDB/Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb  
---  
warnings | Start residue of secondary structure not found: HELIX 13 13 ALA D
35 VAL D 45 1 11  
Start residue of secondary structure not found: HELIX 14 14 SER D 53 TYR D 80
1 28  
Start residue of secondary structure not found: HELIX 15 15 SER D 88 LEU D 98
1 11  
Start residue of secondary structure not found: HELIX 16 16 GLU D 102 THR D
119 1 18  
Start residue of secondary structure not found: HELIX 29 29 ALA H 35 VAL H 45
1 11  
3 messages similar to the above omitted  
  
Chain information for Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb #2  
---  
Chain | Description  
A | No description available  
B | No description available  
C G | No description available  
D H | No description available  
E | No description available  
F | No description available  
I | No description available  
J | No description available  
K | No description available  
L | No description available  
  

> select #2

15784 atoms, 16664 bonds, 4 pseudobonds, 1528 residues, 2 models selected  

> show sel atoms

> style #2 stick

Changed 15784 atom styles  

> ui tool show ISOLDE

> set selectionWidth 4

Chain information for Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb  
---  
Chain | Description  
2.2/A | No description available  
2.2/B | No description available  
2.2/C 2.2/G | No description available  
2.2/D 2.2/H | No description available  
2.2/E | No description available  
2.2/F | No description available  
2.2/I | No description available  
2.2/J | No description available  
2.2/K | No description available  
2.2/L | No description available  
  
Done loading forcefield  

> select #2.2

15784 atoms, 16664 bonds, 4 pseudobonds, 1528 residues, 6 models selected  

> select #2.3

1 model selected  

> select #2.2

15784 atoms, 16664 bonds, 4 pseudobonds, 1528 residues, 6 models selected  

> addh

Summary of feedback from adding hydrogens to
Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb #2.2  
---  
warnings | Not adding hydrogens to /A LYS 37 CB because it is missing heavy-
atom bond partners  
Not adding hydrogens to /A ARG 134 CB because it is missing heavy-atom bond
partners  
Not adding hydrogens to /B LYS 12 CB because it is missing heavy-atom bond
partners  
Not adding hydrogens to /C LYS 13 CB because it is missing heavy-atom bond
partners  
Not adding hydrogens to /C LYS 36 CB because it is missing heavy-atom bond
partners  
19 messages similar to the above omitted  
notes | No usable SEQRES records for
Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb (#2.2) chain A; guessing
termini instead  
No usable SEQRES records for
Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb (#2.2) chain B; guessing
termini instead  
No usable SEQRES records for
Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb (#2.2) chain C; guessing
termini instead  
No usable SEQRES records for
Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb (#2.2) chain D; guessing
termini instead  
No usable SEQRES records for
Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb (#2.2) chain E; guessing
termini instead  
7 messages similar to the above omitted  
Chain-initial residues that are actual N termini: /A LYS 37, /B GLY 11, /C ALA
12, /D THR 32, /E ARG 40, /F GLY 11, /G ALA 12, /H THR 32, /I DT 2, /J DA 1,
/K SER 176, /L MET 1  
Chain-initial residues that are not actual N termini: /K THR 235, /K PRO 577  
Chain-final residues that are actual C termini: /F GLY 102, /I DT 147, /J DA
146  
Chain-final residues that are not actual C termini: /A ARG 134, /B GLY 101, /C
LYS 118, /D ALA 124, /E ARG 134, /G LYS 118, /H ALA 124, /K TYR 580, /K ARG
216, /K ARG 572, /L CYS 76  
1622 hydrogen bonds  
Adding 'H' to /K THR 235  
/A ARG 134 is not terminus, removing H atom from 'C'  
/B GLY 101 is not terminus, removing H atom from 'C'  
/C LYS 118 is not terminus, removing H atom from 'C'  
/D ALA 124 is not terminus, removing H atom from 'C'  
/E ARG 134 is not terminus, removing H atom from 'C'  
4 messages similar to the above omitted  
13337 hydrogens added  
  

> volume #1 step 1

> volume #1 level 2.707

> set bgColor white

> volume #1 level 0.6593

> select #2.2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 6 models selected  

> select #2.2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 6 models selected  

> select #2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 9 models selected  

> select #2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 9 models selected  

> select #2.2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 6 models selected  

> select #2.2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 6 models selected  

> select #2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 9 models selected  

> select #2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 9 models selected  

> select #2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 9 models selected  

> open "D:/Dropbox (NYU Langone
> Health)/LabIgor/Structural/phenix/phenix_mac2/eLBOWx_30/SOP_elbow.cif"

Summary of feedback from opening D:/Dropbox (NYU Langone
Health)/LabIgor/Structural/phenix/phenix_mac2/eLBOWx_30/SOP_elbow.cif  
---  
warning | Skipping chem_comp category: Missing column 'type' near line 18  
  

> open "D:/Dropbox (NYU Langone
> Health)/LabIgor/Structural/phenix/phenix_mac2/eLBOWx_30/SOP_elbow.pdb"

> select #3

49 atoms, 51 bonds, 1 residue, 1 model selected  

> select #2

29121 atoms, 30001 bonds, 4 pseudobonds, 1528 residues, 15 models selected  

> select #3

49 atoms, 51 bonds, 1 residue, 1 model selected  

QFileSystemWatcher::removePaths: list is empty  

> save "D:/Dropbox (NYU Langone
> Health)/LabIgor/Structural/yeastDot1More/SupplementPAPER/Building_010820/Isolde012320/Isolde012320.cxs"

Taking snapshot of stepper: Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb  
Restoring stepper: Ref83_noHydrogen_H4ac5av5_s_pdbset1_H2B120_Cis.pdb  
opened ChimeraX session  

> ui tool show ISOLDE

> set selectionWidth 4

Done loading forcefield  

> select ::name="SAM"

50 atoms, 52 bonds, 1 residue, 1 model selected  
Traceback (most recent call last):  
File "C:\Program Files\ChimeraX 1.1\bin\lib\site-packages\chimerax\ui\gui.py",
line 1574, in <lambda>  
action.triggered.connect(lambda arg, cb = callback: cb())  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\menu\menu.py", line 58, in f  
module.run_script(session)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\menu\prep\parameterise_ligand_with_current_h.py",
line 19, in run_script  
parameterise_residue_with_elbow(sel, include_hydrogens=True,
keep_elbow_files=False)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\phenix\parameterise.py", line 16, in
parameterise_residue_with_elbow  
install_parmed_if_necessary(session)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\parmed\\__init__.py", line 30, in
install_parmed_if_necessary  
install_parmed(session)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\parmed\\__init__.py", line 52, in install_parmed  
'Please install {} and try again. \n\n{}'.format(compiler_package,  
UnboundLocalError: local variable 'compiler_package' referenced before
assignment  
  
UnboundLocalError: local variable 'compiler_package' referenced before
assignment  
  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\parmed\\__init__.py", line 52, in install_parmed  
'Please install {} and try again. \n\n{}'.format(compiler_package,  
  
See log for complete Python traceback.  
  
Traceback (most recent call last):  
File "C:\Program Files\ChimeraX 1.1\bin\lib\site-packages\chimerax\ui\gui.py",
line 1574, in <lambda>  
action.triggered.connect(lambda arg, cb = callback: cb())  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\menu\menu.py", line 58, in f  
module.run_script(session)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\menu\prep\parameterise_ligand_with_auto_h.py", line
19, in run_script  
parameterise_residue_with_elbow(sel, include_hydrogens=False,
keep_elbow_files=False)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\phenix\parameterise.py", line 16, in
parameterise_residue_with_elbow  
install_parmed_if_necessary(session)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\parmed\\__init__.py", line 30, in
install_parmed_if_necessary  
install_parmed(session)  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\parmed\\__init__.py", line 52, in install_parmed  
'Please install {} and try again. \n\n{}'.format(compiler_package,  
UnboundLocalError: local variable 'compiler_package' referenced before
assignment  
  
UnboundLocalError: local variable 'compiler_package' referenced before
assignment  
  
File "C:\Users\marcv\AppData\Local\UCSF\ChimeraX\1.1\site-
packages\chimerax\isolde\parmed\\__init__.py", line 52, in install_parmed  
'Please install {} and try again. \n\n{}'.format(compiler_package,  
  
See log for complete Python traceback.  
  




OpenGL version: 3.3.13560 Core Profile Forward-Compatible Context 26.20.11030.14002
OpenGL renderer: AMD Radeon(TM) Vega 8 Graphics
OpenGL vendor: ATI Technologies Inc.
Manufacturer: HUAWEI
Model: NBLK-WAX9X
OS: Microsoft Windows 10 Home Single Language (Build 18363)
Memory: 7,448,702,976
MaxProcessMemory: 137,438,953,344
CPU: 8 AMD Ryzen 5 3500U with Radeon Vega Mobile Gfx  "
PyQt version: 5.12.3
Compiled Qt version: 5.12.4
Runtime Qt version: 5.12.9
Installed Packages:
    alabaster: 0.7.12
    appdirs: 1.4.4
    Babel: 2.8.0
    backcall: 0.2.0
    blockdiag: 2.0.1
    certifi: 2020.6.20
    chardet: 3.0.4
    ChimeraX-AddH: 2.1.1
    ChimeraX-AlignmentAlgorithms: 2.0
    ChimeraX-AlignmentHdrs: 3.2
    ChimeraX-AlignmentMatrices: 2.0
    ChimeraX-Alignments: 2.1
    ChimeraX-Arrays: 1.0
    ChimeraX-Atomic: 1.6.1
    ChimeraX-AtomSearch: 2.0
    ChimeraX-AxesPlanes: 2.0
    ChimeraX-BasicActions: 1.1
    ChimeraX-BILD: 1.0
    ChimeraX-BlastProtein: 1.0.1
    ChimeraX-BondRot: 2.0
    ChimeraX-BugReporter: 1.0
    ChimeraX-BuildStructure: 2.0
    ChimeraX-Bumps: 1.0
    ChimeraX-BundleBuilder: 1.0
    ChimeraX-ButtonPanel: 1.0
    ChimeraX-CageBuilder: 1.0
    ChimeraX-CellPack: 1.0
    ChimeraX-Centroids: 1.1
    ChimeraX-ChemGroup: 2.0
    ChimeraX-Clashes: 2.0
    ChimeraX-Clipper: 0.15.0
    ChimeraX-ColorActions: 1.0
    ChimeraX-ColorGlobe: 1.0
    ChimeraX-CommandLine: 1.1.3
    ChimeraX-ConnectStructure: 2.0
    ChimeraX-Contacts: 1.0
    ChimeraX-Core: 1.1
    ChimeraX-CoreFormats: 1.0
    ChimeraX-coulombic: 1.0.1
    ChimeraX-Crosslinks: 1.0
    ChimeraX-Crystal: 1.0
    ChimeraX-DataFormats: 1.0
    ChimeraX-Dicom: 1.0
    ChimeraX-DistMonitor: 1.1
    ChimeraX-DistUI: 1.0
    ChimeraX-Dssp: 2.0
    ChimeraX-EMDB-SFF: 1.0
    ChimeraX-ExperimentalCommands: 1.0
    ChimeraX-FileHistory: 1.0
    ChimeraX-FunctionKey: 1.0
    ChimeraX-Geometry: 1.1
    ChimeraX-gltf: 1.0
    ChimeraX-Graphics: 1.0
    ChimeraX-Hbonds: 2.0
    ChimeraX-Help: 1.0
    ChimeraX-HKCage: 1.0
    ChimeraX-IHM: 1.0
    ChimeraX-ImageFormats: 1.0
    ChimeraX-IMOD: 1.0
    ChimeraX-IO: 1.0
    ChimeraX-ISOLDE: 1.1.0
    ChimeraX-Label: 1.0
    ChimeraX-ListInfo: 1.0
    ChimeraX-Log: 1.1.1
    ChimeraX-LookingGlass: 1.1
    ChimeraX-Map: 1.0.1
    ChimeraX-MapData: 2.0
    ChimeraX-MapEraser: 1.0
    ChimeraX-MapFilter: 2.0
    ChimeraX-MapFit: 2.0
    ChimeraX-MapSeries: 2.0
    ChimeraX-Markers: 1.0
    ChimeraX-Mask: 1.0
    ChimeraX-MatchMaker: 1.1
    ChimeraX-MDcrds: 2.0
    ChimeraX-MedicalToolbar: 1.0.1
    ChimeraX-Meeting: 1.0
    ChimeraX-MLP: 1.0
    ChimeraX-mmCIF: 2.2
    ChimeraX-MMTF: 2.0
    ChimeraX-Modeller: 1.0
    ChimeraX-ModelPanel: 1.0
    ChimeraX-ModelSeries: 1.0
    ChimeraX-Mol2: 2.0
    ChimeraX-Morph: 1.0
    ChimeraX-MouseModes: 1.0
    ChimeraX-Movie: 1.0
    ChimeraX-Neuron: 1.0
    ChimeraX-Nucleotides: 2.0
    ChimeraX-OpenCommand: 1.2.1
    ChimeraX-PDB: 2.1
    ChimeraX-PDBBio: 1.0
    ChimeraX-PickBlobs: 1.0
    ChimeraX-Positions: 1.0
    ChimeraX-PresetMgr: 1.0
    ChimeraX-PubChem: 2.0
    ChimeraX-Read-Pbonds: 1.0
    ChimeraX-Registration: 1.1
    ChimeraX-RemoteControl: 1.0
    ChimeraX-ResidueFit: 1.0
    ChimeraX-RestServer: 1.0
    ChimeraX-RNALayout: 1.0
    ChimeraX-RotamerLibMgr: 2.0
    ChimeraX-RotamerLibsDunbrack: 2.0
    ChimeraX-RotamerLibsDynameomics: 2.0
    ChimeraX-RotamerLibsRichardson: 2.0
    ChimeraX-SaveCommand: 1.2
    ChimeraX-SchemeMgr: 1.0
    ChimeraX-SDF: 2.0
    ChimeraX-Segger: 1.0
    ChimeraX-Segment: 1.0
    ChimeraX-SeqView: 2.2
    ChimeraX-Shape: 1.0.1
    ChimeraX-Shell: 1.0
    ChimeraX-Shortcuts: 1.0
    ChimeraX-ShowAttr: 1.0
    ChimeraX-ShowSequences: 1.0
    ChimeraX-SideView: 1.0
    ChimeraX-Smiles: 2.0
    ChimeraX-SmoothLines: 1.0
    ChimeraX-SpaceNavigator: 1.0
    ChimeraX-StdCommands: 1.0.4
    ChimeraX-STL: 1.0
    ChimeraX-Storm: 1.0
    ChimeraX-Struts: 1.0
    ChimeraX-Surface: 1.0
    ChimeraX-SwapAA: 2.0
    ChimeraX-SwapRes: 2.0
    ChimeraX-TapeMeasure: 1.0
    ChimeraX-Test: 1.0
    ChimeraX-Toolbar: 1.0
    ChimeraX-ToolshedUtils: 1.0
    ChimeraX-Tug: 1.0
    ChimeraX-UI: 1.2.3
    ChimeraX-uniprot: 2.0
    ChimeraX-ViewDockX: 1.0
    ChimeraX-Vive: 1.1
    ChimeraX-VolumeMenu: 1.0
    ChimeraX-VTK: 1.0
    ChimeraX-WavefrontOBJ: 1.0
    ChimeraX-WebCam: 1.0
    ChimeraX-WebServices: 1.0
    ChimeraX-Zone: 1.0
    colorama: 0.4.3
    comtypes: 1.1.7
    cxservices: 1.0
    cycler: 0.10.0
    Cython: 0.29.20
    decorator: 4.4.2
    distlib: 0.3.1
    docutils: 0.16
    filelock: 3.0.12
    funcparserlib: 0.3.6
    gdcm: 2.8.8
    grako: 3.16.5
    h5py: 2.10.0
    html2text: 2020.1.16
    idna: 2.10
    ihm: 0.16
    imagecodecs: 2020.5.30
    imagecodecs-lite: 2020.1.31
    imagesize: 1.2.0
    ipykernel: 5.3.0
    ipython: 7.15.0
    ipython-genutils: 0.2.0
    jedi: 0.17.2
    Jinja2: 2.11.2
    jupyter-client: 6.1.3
    jupyter-core: 4.6.3
    kiwisolver: 1.2.0
    line-profiler: 2.1.2
    lxml: 4.5.1
    MarkupSafe: 1.1.1
    matplotlib: 3.2.1
    msgpack: 1.0.0
    netifaces: 0.10.9
    networkx: 2.4
    numexpr: 2.7.1
    numpy: 1.18.5+mkl
    numpydoc: 1.0.0
    openvr: 1.12.501
    packaging: 20.4
    parso: 0.7.1
    pickleshare: 0.7.5
    Pillow: 7.1.2
    pip: 20.2.2
    pkginfo: 1.5.0.1
    prompt-toolkit: 3.0.7
    psutil: 5.7.0
    pycollada: 0.7.1
    pydicom: 2.0.0
    Pygments: 2.6.1
    PyOpenGL: 3.1.5
    PyOpenGL-accelerate: 3.1.5
    pyparsing: 2.4.7
    PyQt5-commercial: 5.12.3
    PyQt5-sip: 4.19.19
    PyQtWebEngine-commercial: 5.12.1
    python-dateutil: 2.8.1
    pytz: 2020.1
    pywin32: 228
    pyzmq: 19.0.2
    qtconsole: 4.7.4
    QtPy: 1.9.0
    RandomWords: 0.3.0
    requests: 2.24.0
    scipy: 1.4.1
    setuptools: 49.4.0
    sfftk-rw: 0.6.6.dev0
    six: 1.15.0
    snowballstemmer: 2.0.0
    sortedcontainers: 2.2.2
    Sphinx: 3.1.1
    sphinxcontrib-applehelp: 1.0.2
    sphinxcontrib-blockdiag: 2.0.0
    sphinxcontrib-devhelp: 1.0.2
    sphinxcontrib-htmlhelp: 1.0.3
    sphinxcontrib-jsmath: 1.0.1
    sphinxcontrib-qthelp: 1.0.3
    sphinxcontrib-serializinghtml: 1.1.4
    suds-jurko: 0.6
    tables: 3.6.1
    tifffile: 2020.6.3
    tinyarray: 1.2.2
    tornado: 6.0.4
    traitlets: 5.0.4
    urllib3: 1.25.10
    wcwidth: 0.2.5
    webcolors: 1.11.1
    wheel: 0.34.2
    WMI: 1.5.1

[Tristan Croll]

Oops. What ISOLDE is *trying* to tell you is that you'll need to install Visual Studio before you can install ParmEd (because it's only available as a source distribution on the PyPI). But clearly I messed up the construction of the error message.