Don't worry, that's where I come in vs Don't worry; that's where I come in

I know the second one is correct: Don’t worry; that’s where I come in. As they are both independent clauses.

My question is: would it be incorrect to say: "Don’t worry, that’s where I come in"? Or is it one of those which is technically incorrect but generally accepted? As I feel like the second version is a bit too formal for general use.

Thanks!