I asked ChatGTP about the errors I was getting upon load and here's what it's advised me (spoiler alert, they're from this mod):

The error message you're encountering in RimWorld indicates an issue with the initialization of a DefOf type, specifically SoundDefOf. In RimWorld, DefOfs are references to game definitions (Defs) used for easier coding. The error suggests that the SoundDefOf is being used before all the definitions (Defs) have been fully loaded and initialized by the game.

This is often caused by a mod attempting to access or use a game definition too early in the loading process. The hint provided in the error message suggests that the mod author should not use DefOfs as default field values in their Defs. Instead, they should resolve them in the ResolveReferences() method, which is called after all Defs are loaded.

To resolve this issue:

Identify the Mod: The error message mentions Merthsoft.DesignatorShapes, which might be the mod causing the issue.

Check for Updates: Ensure that the mod is updated. Sometimes, mod authors release fixes for these kinds of issues.

Contact the Mod Author: If the problem persists, consider reaching out to the mod author with the error details. They might need to adjust how they are using DefOfs in their mod.

Temporarily Disable the Mod: If the error significantly impacts your gameplay and there's no immediate fix, consider disabling the mod until an update or fix is available.