I actually used a macro to reproduce this crash but the first time it was an accident (well almost)
If you place and manage to break a sign before the sign menu pops up the game automatically crashes... I have no screen shots as you can't screen shot a crash and I can't record it due to my weak system
Incomplete without a crash report from (minecraft/crash-reports/crash-<DATE>-client.txt). Please attach it to this ticket so that we can diagnose your issue.