Issue: Can delete a line if used as an angle in 'CurveIntersectAxis' tool

Seamly v0.6.0.1 built on Mon Dec 14 2020

Problem: The line that was used as the angle (or “Axis”) value for a subsequent “CurveIntersectAxis” point can be. The line was created prior to the intersection point, so this shouldn’t be possible. IssueDeletePointFromIntersectCurveAxis.val (1.5 KB)

Desired behavior: The ‘Delete’ option for the Line referenced in the formula to calculate the angle should be disabled.

Screenshots, etc.:
Point A4 was created from curve = Spl_A4_A2, base point = A, and angle = AngleLine_A_A2:

Delete option for Line_A_A2 is Enabled:

After Line_A_A2 is deleted, this ErrMsg appears with the prompt to Fix the Formula. It’s possible to either select ‘Undo’ or fix the formula - the pattern is fine. If ‘Cancel’ is selected the pattern (& Seamly2D) crashes but the pattern will re-open in the state prior to deleting the line. But the line should never have been deleted, there was another object which references it in it’s formulas.


Here’s the issue in github: