The mod FMLMod:MyMod{} is attempting to register a block whilst it it being constructed. This is bad modding practice - please use a proper mod lifecycle event.

 

Mod is registering 24 blocks NOT in MainMod class, but in it's constructor class BlockBase.class - it allows me to load tons of blocks while not writing GameRagistry to each and everyone of them. Everything is working well, but I don't like having warnings in my console.

 

Tell me honestly: Is there a chance this can crash my game? ANY?

It's about how you read the sentence. You (and me too) thought GameRegistry was yelling about that you register the block before it was fully initialized. However, after research, it seems to be about you registering a too early init stage. Block registry should be done in the PreInit, but you've done it before that. Have you initialized your blocks statically? So "public static Block test = new BlockBase(parms);"  ?

 

So calling GameRegistry from within your constructor is fine, calling it before the PreInit phase isn't.