Crash when reordering LPE

Steps to reproduce:

• open Inkscape
• draw the shape with pen tool
• Add LPE Mirror symmetry
• change to fuse shapes
• Add LPE Rotation copies
• adjust centre
• Add LPE Fillet/chamfer
• add Fillet manually to one shape
• change order of LPEs (Fillet/chamfer is first)

What happened?

• Inkscape crashed

What should have happened?

• Inkscape should not crash
• this happens for reordering any 3+ LPEs not just Fillet/chamfer

Inkscape Version and Operating System:

• Inkscape Version: 1.0alpha (7076368, 2019-01-18)
• Operating System: WIN 10
• Operating System version: 1809

video of the bug reproduction: https://streamable.com/s7fgv