Regarding Error handling

Is there a recommended way to handle errors without printing them directly to the screen. For an error in file mysqli, it's throwing: 

echo $error . "\n";

Would I be able to amend this code to comment out the "echo", or log the echo instead of displaying it? Are there any known compatability issues with this. I saw in the code it directed to upload custom files (code) to the specified directory.

Hello.

Where do you see this (what file and line number, and what version of Composr)? It might be a debug line that never got removed.