G-code Viewer - Error while loading .gcode (all files "does not contain valid gcode")

[JohanAR]

Describe the bug
If I use File -> G-code preview... from SuperSlicer main window the file I choose is loaded in the g-code viewer.
But if I use File -> Open G-code... from the viewer it will say that the file does not contain valid gcode, regardless of which file I choose, even if it is a file that a could view when opening through the main window.
Using File -> Reload from disk in the viewer will also produce the same error message, for any successfully viewed file that I opened from the main window.

To Reproduce
Steps to reproduce the behavior:

1. Go to File -> G-code preview... and select a valid .gcode file
2. The .gcode file is rendered in the viewer
3. Go to File -> Open G-code... and select the same (or any other) .gcode file

>> Project File <<
Uploading a .gcode file that I could preview from the main SuperSlicer window, but fails to load from inside the viewer
gcode_with_arcs.zip

Expected behavior
The file is previewed

Screenshots
Ping me on Discord if this doesn't happen for anyone else

Desktop (please complete the following information):

• OS: Xubuntu 21.04
• Build: SuperSlicer_2.3.57.0