Stray pixels in glowing pause menu shine

[Koopa1018]

Describe the bug
After fixing the rewritten glow shader multiple times, the level info screen's shine icon looks like this:

Note the stray pixels on the left side, compared to the right. Based on the bugs that came before, it seems to be outlining as though the left column of texels is being extended to the edge of the mesh.

This icon is the only thing exhibiting this bug. Every other glowing object in the game looks correct, though it can be reproduced in shine sprites by setting their material's Cell Count to (1, 1).

To Reproduce

1. In-game, open the pause menu.

Expected behavior
The shine icon appears

Screenshots
See above.

System Information

• OS/Browser: Windows 10, Godot editor 4.1
• Game version: Fix Level Designer bugs #286
• Other specs:

Additional context
This might possibly be a lot easier if the textureSize(...) function returned anything other than 0.