Godot freezes with "Interface -> Custom Font" set

[TX256]

Operating system or device, Godot version, GPU Model and driver (if graphics related):
Windows 10, Godot 3.

Issue description:
A daily build of Godot from around a week ago broke the custom fonts (the global UI font - NOT the text editor font).

This seems to be related to the script editor, because the Godot window freezes (not responding) as soon as I open any script - while having a custom font for the UI.

[reduz]

This would probably need bisecting to find when and why it broke

[djrm]

this might be fixed by #12794

[vnen]

Was this solved?

[mhilbrunner]

I can no longer reproduce this as of most recent master, but there is something weird.

I set the font, save, reload the editor. The project manager then shows up correctly using the custom font, as does the editor after loading a project.

However, after a few seconds the editor switches back to using the default font everywhere.

[mhilbrunner]

Seems something after Godot 3 beta2 caused the issue above. With beta2, custom fonts work correctly. No hangs. With current master, there are no hangs either, but custom fonts switch back to default after a few seconds.

[akien-mga]

Should now be fully fixed with #15073.