okay, it looks like it is custom code related.
Somehere in the app this code is used:
- ( /** add mandatory asterisk ? **/
- arFields[i].required
- ?
- ''
- :
- ''
- ) +
It's the question mark in the comment field combined with the
fact that it is placed in a ternary operator that is causing the
compressor to fail.
Hope this may help others.