To completely remove the message, you'll need to make a small tweak to the game files. Follow these steps:

Open Garry's Mod in your Steam library.
Click Browse Local Files to open the game’s directory.
Navigate to: garrysmod > lua > menu.
Inside the menu folder, find the file named "errors.lua".
Delete errors.lua.
Restart Garry's Mod, and... WOW! No more pesky error messages! 🎉

Q: Will this fix the actual errors, or just hide the message?
A: This only removes the pop-up messages. The errors themselves will still exist and can be seen in the console and the Errors tab.

Q: Will deleting errors.lua break my game?
A: No, removing this file only stops the pop-up error messages from appearing. The game will continue to function as usual.

Q: How do I restore the error messages if I want them back?
A: You can restore the messages by verifying your game files:

Right-click Garry’s Mod in your Steam library.
Go to Properties > Installed Files.
Click Verify Integrity of Game Files.
This will redownload errors.lua and restore the messages.

Q: Will this work after a game update?
A: If a game update restores errors.lua, you will need to delete it again.