Unpicking "Session Did Not Load Successfully" errors

Seems I'm having a few teething problems with Ardour 4.1 compared with previous
releases.

Ardour crashed during recording and now the session won't load again.

> Session "studio/PatCo/Track2 (snapshot Track2)" did not load successfully

As it's not actually crashing there's no backtrace to present. Is there
anything I can do to get a bit more information out of it? The .bak files
also failed.


Note, during loading I get these errors, but I get them for any session so
I'm assuming they're a red herring:

lilv_world_add_plugin(): error: Duplicate plugin <https://community.ardour.org/node/7596>
lilv_world_add_plugin(): error: ... found in file:///opt/Ardour-4.1.0/lib/LV2/reasonablesynth.lv2/
lilv_world_add_plugin(): error: ... and      file:///usr/lib/lv2/reasonablesynth.lv2/
Scanning folders for bundled LV2s: /opt/Ardour-4.1.0/lib/LV2
lilv_world_add_plugin(): error: Duplicate plugin <https://community.ardour.org/node/7596>
lilv_world_add_plugin(): error: ... found in file:///opt/Ardour-4.1.0/lib/LV2/reasonablesynth.lv2/
lilv_world_add_plugin(): error: ... and      file:///usr/lib/lv2/reasonablesynth.lv2/
error: failed to expand CURIE `pprops:hasStrictBounds'
error: attempt to add quad with NULL field
error: failed to expand CURIE `pprops:hasStrictBounds'
error: attempt to add quad with NULL field
error: failed to expand CURIE `units:unit'
error: failed to expand CURIE `units:db'
error: attempt to add quad with NULL field
error: failed to expand CURIE `units:conversion'
error: attempt to add quad with NULL field
error: failed to expand CURIE `units:to'
etc.