Stem slashes misplaced on notes without hooks or beams

[XiaoMigros]

Issue type

Engraving bug (incorrect score rendering)

Bug description

When adding acciaccaturas and changing their durations to flag/beamless notes, the stem slash is misplaced:

For quarter and half notes, the end anchor for the line is not calculated, because those points are determined by either the beam or hook positions.
For whole notes the situation is worse, those have both line anchor points set to (0,0) because all points are calculated off the bounding box of a stem, which is not generated in this case.

Steps to reproduce

1. Create a new score
2. Add an acciaccatura to a note
3. Change its duration to a quarter note or large

Screenshots/Screen recordings

No response

MuseScore Version

4.2.0

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

Windows 10

Additional context

No response