It is crashing in the mp4/m4a plugin from your dump.
My guess is that the file was corrupted after MC27 imported it and MC29 is crashing when it gets to that file, either on auto-import or when building it's thumbnail.
You can turn on logging in MC.
Help->Logging
Run MC, then when it crashes, run it again then do Help->Logging again and "report problem"
You can email the logs to me
bob (at) jriver (dot) com
Another thing to check, make sure that your
Mac System Preferences->Security & Privacy->Files and Folders
allows MediaCenter29 access to all of the locations your material is stored.