I have been experiencing this issue with ReplayMod where it opens upon initial installation, but every time I try to restart the client, it can't open the "Mojang" screen without crashing. I have sourced the issue to ReplayMod as no matter what combination of Fabric mods I use, that is the only one that crashes on client start. I also cannot find the crash repot in my Minecraft folder. I am using MacOS Mojave 10.14.5.
In the log it says: Process crashed with exit code 6