I'd call it an unnatural sentence without a clear meaning.
I don't agree this time - in the right context.
A: You didn't wake me in time, and I missed the bus.
B: If you missed it, I'm not responsible for that.
Here 'if' has a meaning similar to, 'If you missed it, and I accept that you did'.
Here's a similar usage:
A: I believed every word he said.
B: Well, if you believed everything, you're a bigger fool than I thought you were.
Like many sentences with an
if- clause, it's difficult to slot this into the traditional five classes of conditionals, zero, first, second, third and mixed. But then I don't think the traditional five classes are helpful or accurate.