Created attachment 102159 [details] GDB output All is said in summary. This is reproducible on 2 computers. I am using Archlinux packages that come without debug symbols. Nevertheless I attached gdb output.
Does it happen with every keyboard layout? Here, the Alt key has no influence on simple digit keys, and Kate simply inserts '0' and '1' chracters.
I think this is a duplicate of the build plugin crash when invoking lookup without an active project (and tool view) *** This bug has been marked as a duplicate of bug 371976 ***