With the attached example code I can trigger two different assertions
somewhere down the line of redisplay():

1) dispnew.c:1405: Emacs fatal error: assertion failed: row >= 0 && row < matrix->nrows

2) xdisp.c:17524: Emacs fatal error: assertion failed: row->enabled_p


Unfortunately I could not further isolate the elisp code which eventually
causes these assertions to fail. The following packages from MELPA are
involved: lua-mode, polymode. (version numbers see example code)

This is the example code triggering the mentioned assertions.