Crash while editing Kerning in SVG Font Editor

Steps to reproduce:

issue 1

• open sharpeo_font.svg

or create two glymps on with paths and one empty

• open SVG font editor
• go to kerning tab
• select two glyphs (a and b)
• click add the pair
• crash

issue 2

• create two glyphs (both with geometry)
• open SVG font editor
• go to kerning tab
• crate pair (a and b)
• than create new pair (b and a)
• crash

What happened?

crash

What should have happened?

not crash

Inkscape Version and Operating System:

• Inkscape Version: 1.1-dev (04087178, 2020-01-19) , 0.92.4
• Operating System version: win 10