Crash when attempt to move slur anchor

[BLumia]

Issue type

Crash or freeze

Description with steps to reproduce

1. Open the mscz file provided in the attachment below
2. Click any slur on the sheet (not TAB)
3. When the slur is selected, press Shift+↓ (shift + arrow down)
4. See crash

Supporting files, videos and screenshots

crash.zip (see the reproduce steps above to see how to use this attachment)

2024-12-22.17.01.17.mov

What is the latest version of MuseScore Studio where this issue is present?

4.4.4

Regression

I was unable to check

Operating system

macOS 15.1.1, Windows 11 24H2, Arch Linux rolling

Additional context

#25777 fixes the crash by adding a nullptr check.

The bug is tested under both Windows, macOS and Linux, the fix (PR) linked above was tested under Arch Linux.

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible