[Issue]: FalseTweaks 3.9.x crashes when OptiFine filename is changed

[XMxmx111]

Description

Found a weird bug with FalseTweaks 3.9.0 + OptiFine HD_U_E7. Game crashes during startup if I rename OptiFine's jar file (like changing OptiFine_1.7.10_HD_U_E7.jar to just OptiFine.jar). With the original filename, it works fine.

Tried updating to 3.9.7 hoping it was fixed, but same crash happens.

Using 3.9.x instead of newer versions because need Neodymium for performance, Beddium doesn't work with OptiFine :’(

fml_client_latest.log, and crash reports, if any.

minecraft-exported-crash-info-2025-12-26T18-45-10.zip

I have submitted the required files

• I confirm that i have attached the required log files as a github attachment, and not as a pastebin/mclogs link.