Version-Release number of selected component:
meld-3.17.2-1.fc26

Additional info:
reporter:       libreport-2.9.1
cmdline:        /usr/bin/python3 /usr/bin/meld --output=app/app/models.py ./app/app/models_LOCAL_32172.py ./app/app/models_BASE_32172.py ./app/app/models_REMOTE_32172.py
crash_function: after_text_insert_text
exception_type: TypeError
executable:     /usr/bin/meld
kernel:         4.11.11-300.fc26.x86_64
runlevel:       N 5
type:           Python3
uid:            1000

Truncated backtrace:
filediff.py:774:after_text_insert_text:TypeError: Argument 2 does not allow None as a value

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/meld/filediff.py", line 774, in after_text_insert_text
    starting_at = buf.get_iter_at_mark(start_mark).get_line()
TypeError: Argument 2 does not allow None as a value

Local variables in innermost frame:
start_mark: None
textlen: 101
newtext: '        from gt2_games.event import GameEventSchema\n        from gt2_games.exc import EventLoadError\n'
it: <Gtk.TextIter object at 0x7fb4580245e8 (GtkTextIter at 0x5596955e5f70)>
buf: <meldbuffer.MeldBuffer object at 0x7fb4594c4ca8 (MeldBuffer at 0x7fb46400ba00)>
self: <filediff.FileDiff object at 0x7fb4594bad38 (FileDiff at 0x5596948552c0)>