Error closing Help Viewer when page has 'page closed' URLs

[pett]

The following bug report has been submitted:
Platform:        Darwin-18.7.0-x86_64-i386-64bit
ChimeraX Version: 0.92 (2020-01-27)
Description
Closed a help viewer with two tabs

Log:
UCSF ChimeraX version: 0.92 (2020-01-27)  
© 2016-2020 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open 2519 fromDatabase pubchem

PubChem entry 2519  
  
  
Traceback (most recent call last):  
File
"/Users/chimera/Applications/ChimeraX_Daily.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/ui/widgets/htmlview.py", line 303, in interceptRequest  
self._callback(info)  
File
"/Users/chimera/Applications/ChimeraX_Daily.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/ui/widgets/htmlview.py", line 86, in _intercept  
return interceptor(request_info, *args)  
File
"/Users/chimera/Applications/ChimeraX_Daily.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/help_viewer/tool.py", line 308, in intercept  
view=self.tabs.currentWidget())  
RuntimeError: wrapped C/C++ object of type QTabWidget has been deleted  
  
RuntimeError: wrapped C/C++ object of type QTabWidget has been deleted  
  
File
"/Users/chimera/Applications/ChimeraX_Daily.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/help_viewer/tool.py", line 308, in intercept  
view=self.tabs.currentWidget())  
  
See log for complete Python traceback.  
  




OpenGL version: 4.1 ATI-2.11.21
OpenGL renderer: AMD Radeon Pro 575X OpenGL Engine
OpenGL vendor: ATI Technologies Inc.

[Greg Couch]

Appears to be a race condition in Qt WebEngine implementation where a QWebEngineUrlRequestInterceptor is being called after the QWebEnginePage has been destroyed. Fixed by checking parent tab widget has already be destroyed or not.