I think you mistyped; the if and else blocks are the same.

You could have an issue, depending on the rest of your code, that the simulator uses an initial guess of 0 for the branch current.  Then again, maybe not, since it's the same model code independent of what's driving.

You probably need to look more closely at your probes and sources (contributions).  You might have something that looks like two current sources in series with a very slight mismatch in the sourced current.  What if you put in a huge resistance in parallel, or shrink the 1e-12 so that it's less than abstol?