Got a crash when undoing a resize of a mix. [full-log.txt](/uploads/d9668eae44f71a79c55005eac8ce7c68/full-log.txt). ``` // ADJUSTING EFFECT LENGTH, LOGUNDO true , 0 / 0 - 12 , 13 ---------- ----------- // ADJUSTING EFFECT LENGTH, LOGUNDO true , 0 / 0 - 4 , 5 ASSERT: "m_snaps.count(position) > 0" in file /home/farid/kdenlive/src/timeline2/model/snapmodel.cpp, line 26 ```  When recovering the project and trying to delete the mix or moving a clip away from another I also get a crash with only this info: [log-2.txt](/uploads/e0239d04749ef3eb04f6e41f317e742e/separate-log.txt) ``` = = SET EFFECT PARAM: "rect" = 0=-7097 -7325 21651 12178 1.000000 ASSERT: "!m_playlists[sourcePlaylist].is_blank_at(position) && m_playlists[destPlaylist].is_blank_at(position)" in file /home/farid/kdenlive/src/timeline2/model/trackmodel.cpp, line 127 ```