For certain files with grouped objects containing pattern fills,
ungrouping consistently crashes with a SIGTRAP and the following error
message:
(inkscape:4801): glibmm-ERROR **:
unhandled exception (type std::exception) in signal handler:
what: basic_string::_M_construct null not valid
fish: 'inkscape Map_Paris-reduced-4-pl…' terminated by signal SIGTRAP (Trace or breakpoint trap)
This is reported upstream as #1677486 from 2017-03-30, currently open.
The report includes a test file at
https://bugs.launchpad.net/debian/+source/inkscape/+bug/1677486