In SourceTree 1.6.15003 beta, clicking the Terminal button causes SourceTree to crash and terminate itself.

A fatal error is recorded in sourcetree.log (see attached).

This seems to occur regardless of whether embedded or system git is selected, but can be worked around to some extent by unchecking "Use Git Bash as default terminal" in SourceTree's Git options.

P.S. I've followed the help text on issue priorities but I'm not sure this particular issue really is critical. Someone can change this to minor if more appropriate.