Currently still trying to find which mod has it but here is the error message

Failed to load mods: smart-enemy-ai/data/validate.lua:56: [smart-enemy-ai] would break player turret: uranium-shotgun-pellet (player ammo shotgun-shell) has projectile-block layer
stack traceback:
[C]: in function 'error'
smart-enemy-ai/data/validate.lua:56: in main chunk
[C]: in function 'require'
smart-enemy-ai/data-final-fixes.lua:16: in main chunk

After a 'clean' reload of mods error stopped occuring

Think I found the mod that triggers this is the Fulgoran Enemies mod

Good catch. Fulgoran Enemies adds Space-Age biter variants on Fulgoro, and several of them are styled as ranged "energy" attackers; one or more of those reuses a vanilla player projectile prototype (here uranium-shotgun-pellet) in their attack chain instead of defining their own.

I implemented a clone-and-rewire fix that is mod-agnostic so it'll handle any other mod that does the same trick (the log line will name the projectile so we can see it).

Error still occurs with Fulgoran Enemies mod. There might be an additional thing because i do have a shield mod as well

So found a weird interaction if both Fulgoran Enemies and Combat Tweaks and Additions is on it shows the error however if only one of them is active at a time it works ok

Have you tried the newest Version?

Yes this was on 8.5.3 and to also check it also happens in older versions

Ok i have to look deeper. Combat Tweaks and Additions and Smart work together?

Yes tried that configuration and Smart Ai works with one or the other but not both, both(without Smart) also work fine together

smart-enemy-ai + mod A alone (the one with the enemy that fires uranium-shotgun-pellet): the projectile prototype uranium-shotgun-pellet doesn't exist (combat-tweaks would have added it, but it's not loaded). Our scan walks the enemy attack, calls patch_existing_projectile("uranium-shotgun-pellet"), hits if not p then return end at line 75 of prototype-scan.lua, and bails silently. No layer added, validate sees nothing — clean load.

smart-enemy-ai + mod B alone (combat-tweaks-improvements): the player projectile + player ammo exist, but no enemy references the projectile. Our scan walks every data.raw.unit/turret with subgroup="enemies", finds zero references to uranium-shotgun-pellet, never patches it. Validate finds the player ammo, looks at the projectile, sees no smart-enemy-ai layer — clean load.

Could you give me a full mod list? Somehow player ammo uranium-shotgun-pellet is given to enemies from Fulgoran Enemies. Because of Wallblock that blocks enemy projectiles but lets player projectile pass a projectiule that is player and enemy at the same time crashes the game.

Or post me a current.log when this crash happens

Having both mods on works with 8.5.5. It might be because of the Enemy Mod Harmonizer since from what i understand it makes a 'unified' readable mask for projectiles, have not tried to disable that instead of Fulgoran Enemies and Combat Tweaks though.

I rewrote the whole blocking mechanism and now only register enemy projectiles. Now i doesnt matter if a player and an enemy use the same projectile.