Segmentation fault when trying to plot something

Description:

After the upgrade to 9.1.0-1 I am unable to plot anything, as the program instantly segfaults when calling plot or fplot. This happens both when running the GUI and when calling Octave from the command line, and had been replicated by at least one other user. Also, I should mention that:

• This happens with the qt graphic toolkit, which is the default. If needed I'll try to reproduce with other graphic backends
• This happens both on wayland (wlroots) and on X11

Additional info:

• package version(s): 9.1.0-1
• config and/or log files:
  • Output of bt full, terminal session: terminal
  • Stack trace from @gromit shared on IRC: stacktrace
• link to upstream bug report, if any: I didn't find anything in the upstream bug tracker, though admittedly I didn't spend that much time searching

Steps to reproduce:

1. Open Octave (octave --gui or just octave)
2. Try to plot something from the command window, for instance by calling fplot('sin')
3. Observe the crash