Crash when `color_schemes.<T>.background_image.path` points to non-existent file

[whisperity]

Contour Terminal version

0.3.9.4459

Installer source

Github: CI actions

Operating System

Ubuntu 20.04 & 22.04

Architecture

x86-64

Other Software

No response

Steps to reproduce

Set the used colour scheme's background_image.path to a file that does not exist, e.g., /home/whisperity/nope.png.

Expected Behavior

A warning that there is no background image that could be loaded, but go forward without a background image. Or deterministically put an error texture as background, like in Source:

Actual Behavior

Segmentation fault during startup (without pointers to the error cause).
At least with debug enabled, the crash visually happens during something related to the background:

[2022-12-20 10:29:17.965614] [gui.display] configureAtlas: 1024x2048 RGBA
[2022-12-20 10:29:17.965639] [vt.renderer] Configuring texture atlas.
[2022-12-20 10:29:17.965643] [vt.renderer] - Atlas properties     : tile size 10x20, format RGBA, direct-mapped 116
[2022-12-20 10:29:17.965647] [vt.renderer] - Atlas texture size   : 1024x2048 pixels
[2022-12-20 10:29:17.965650] [vt.renderer] - Atlas hashtable      : 4096 slots
[2022-12-20 10:29:17.965653] [vt.renderer] - Atlas tile count     : 10404 = 102x * 102y
[2022-12-20 10:29:17.965656] [vt.renderer] - Atlas direct mapping : enabled (for text rendering)
[2022-12-20 10:29:17.965823] [gui.display] Blurring background image: /home/whisperity/nope.png
[2022-12-20 10:29:17.968240] [gui.display] Blur: Loading shader source :/contour/display/shaders/simple.vert
[2022-12-20 10:29:17.968321] [gui.display] Blur: Loading shader source :/contour/display/shaders/blur_gaussian.frag
[2022-12-20 10:29:17.968927] [gui.display] Blur: Loading shader source :/contour/display/shaders/simple.vert
[2022-12-20 10:29:17.968957] [gui.display] Blur: Loading shader source :/contour/display/shaders/dual_kawase_up.frag
[2022-12-20 10:29:17.969289] [gui.display] Blur: Loading shader source :/contour/display/shaders/simple.vert
[2022-12-20 10:29:17.969307] [gui.display] Blur: Loading shader source :/contour/display/shaders/dual_kawase_down.frag
[2]    7788 segmentation fault  contour debug '*'

Additional notes

No response

[christianparpart]

NB: That should be easily fixable without any too deep knowledge. :)