Crash, when kerning same characters

[Csala Péter]

Version: Inkscape 0.92
OS: Windows 8.1

Steps:
1. Open inkscape version 0.92
2. Open SVG Font editor, create a new font and add a glyph
3. Create a path (it works with a spiral too)
4. Set the glyph to that curve
5. Go to kerning
6. Select the same character twice
7. Somitmes clicking the button next to it causes the crash, sometimes clicking the new pair

This doesn't always happens, but if it does, it stays that way

[Csala Péter (gorbit99)]

I attached a file with the same problem
Even trying to select the font displays a "blank" error message with an invisible text and invisible ok button

[Csala Péter (gorbit99)]

Update:
The cause of the problem is the sample text, in my example file having no sample text doesn't cause a crash, but whenever I write 2 of the same characters next to eachother, it crashes

[Joshua Tellez (rebelliousrobot)]

So, I have an empty Sample Text box, but when I edit the kerning, it still crashes.

[Joshua Tellez (rebelliousrobot)]

To specify, I was using the latest version.