gmarkup: Fix crash in error handling path for closing elements
If something which looks like a closing tag is left unfinished, but isn’t paired to an opening tag in the document, the error handling code would do a null pointer dereference. Avoid that, at the cost of introducing a new translatable error message.
Includes a test case, courtesy of pdknsk.
Signed-off-by: Philip Withnall withnall@endlessm.com
Closes #1461 (closed)
This includes the commit from !204 (merged), since otherwise they’d conflict. That’s already been reviewed, so just review the head commit here please.