Ripple Delete Intermittently Causes Crash

[khinch]

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OS and Version (please complete the following information):

• Operating System: Linux (NixOS 25.05)
• Shotcut Version: 25.05.11 (installed via Nix packages)

Describe the bug
Ripple delete causes intermittent crash

Steps To Reproduce

1. In a new project, import a video clip
2. Create some video tracks
3. Split the clip in a few places
4. Move the segments into the other video tracks
5. In the spaces between the clips, Right-click -> Ripple delete
6. Error is seen: Intermittently Shotcut will crash during a ripple delete operation
   Note: On opening Shotcut after the crash, and opening the saved project, Shotcut will usually crash again even if the user opts not to recover the operations.

Expected behavior
Ripple delete works successfully every time and does not crash Shotcut

Screenshots

Shotcut.Ripple.Delete.Crash.mp4

[KHouse75]

I can confirm this issue but it's not just a ripple. It'll crash when dragging segments and when undoing ripple deletes as well as other undo operations. Crashing with undo happens very frequently.

I've had this happen on 3 different linux distributions on 3 different systems with the latest shotcut version as well as older versions.