Crash when previewing malformed regular expression when compiling

[worstje]

Using a malformed regular expression in the transformation screen and clicking 'preview' causes the program to crash.

In case it is specific to the exporter chosen: I was messing around with the Pandoc 'HTML' export.

Traceback:

C:\Portable\Manuskript>manuskript.exe
Debug: Web rendering engine used: QWebView
Running manuskript version 0.8.0.
Note: No translator found or loaded for locale en_US.
Loading: .msk
Detected file format version: 1. Zip: True.
Project loaded.
Traceback (most recent call last):
File "manuskript\ui\exporters\exporter.py", line 101, in preview
File "manuskript\exporter\pandoc\HTML.py", line 33, in preview
File "manuskript\exporter\pandoc\abstractPlainText.py", line 36, in src
File "manuskript\exporter\manuskript\plainText.py", line 44, in output
File "manuskript\exporter\manuskript\plainText.py", line 174, in concatenate
File "manuskript\exporter\manuskript\plainText.py", line 151, in concatenate
File "manuskript\exporter\manuskript\plainText.py", line 217, in processText
File "c:\python34\lib\re.py", line 179, in sub
File "c:\python34\lib\re.py", line 294, in _compile
File "c:\python34\lib\sre_compile.py", line 568, in compile
File "c:\python34\lib\sre_parse.py", line 780, in parse
File "c:\python34\lib\sre_parse.py", line 377, in _parse_sub
File "c:\python34\lib\sre_parse.py", line 728, in _parse
File "c:\python34\lib\sre_parse.py", line 377, in _parse_sub
File "c:\python34\lib\sre_parse.py", line 730, in _parse
sre_constants.error: unbalanced parenthesis

Expected behavior:

A popup that tells me what is wrong and ideally also how to fix it. For example, disabling the regular expression option will not cause the crash and cause pandoc to complain about me failing to properly specify a title.

[gedakc]

This sounds similar to recently created Pull Request #486 - Don't crash if a typo is made in the exporter's regular expression.

Are you able to test using the code change in the above listed PR?

[kakaroto]

I checked an unbalanced parenthesis and confirm it's caught (the sre_constants exception is caught by re.error). I've also added the error message to the dialog and it's much more helpful now.

[gedakc]

I confirmed the crash on compile / export preview with an invalid regexp transformation.

I also confirmed that PR #486 prevents the crash and pops up a dialog box with an error message.