tql_internal should have proper error handling

[Lamby777]

Currently there's just .expect() and .unwrap() spam to get stuff done quick.

If the internal crate should ever be exposed to crates.io for people to write their own launchers, it should return actual errors so people can show error messages instead of crashing.

Not a priority right now, I'm only returning errors where I personally need them for tql_gui.