Why are the included song files 0 Bytes in size?

If they are needed. It is a unsuccessful atempt to recover module data after the crash.

If they are needed.

There is not a whole lot of information I can deduce from a 0-byte file, I hope you are aware of that. ;)

None of these are crashes but they are assertion failures. This information is crucial and cannot be directly deduced from the crash dump alone, so always include error.txt for all crashes, not just one. Having info.txt also makes finding the correct mptrack.exe and debug files much easier, so please do not omit any of the text files in the future.

Also please do include the settings files written to the crash directory.
In any case, in order to make hopefully any sense out of this particular problem, I will probably also need the trace log (which is disabled by default). Thus, if you can reproduce the problem at all, please enable [Debug]TraceEnable=1 and restart OpenMPT (see https://wiki.openmpt.org/Manual:_Hidden_Settings#.5BDebug.5D ). And then reproduce again and provide the generated files of that crash.

Please test the following:
A full dump made manually with VS (from yesterday, captured before killing OpenMPT):
https://www.dropbox.com/s/y6z4aanv2t1q6xi/mptrack-20171122-1954_r9323.7z?dl=0

Another automatic dump from OpenMPT (seems corrupted): https://www.dropbox.com/s/y6z4aanv2t1q6xi/mptrack-20171122-1954_r9323.7z?dl=0

Meanwhile, I will try to reproduce again using your recommendations.

New attempt with debug trace enabled:

https://www.dropbox.com/s/4sf88foey2d3fzg/2017-11-23%2013.26.51.7z?dl=0

Status update: The problem is related to the plugin bridge and not trivial to fix.

The plugin bridge has been considerably reworked for OpenMPT 1.29, and while I no longer have the debug symbols to exactly verify what went wrong in this crash dump, I remember that the crash was related to the architectural problem that shoudl be solved by r12029. Let me know if there are still crashes with the plugin bridge in the OpenMPT 1.29.00.28 or later.