[translation] add Exception to catch type inference fail case
[translation] add Exception to catch type inference fail case

Type inference cannot currently handle the case where the RHS is a slice
with a bitwidth > 1.  This exception catches that case to prevent sneaky
translation bugs.

Abhinav117/pymtl,Abhinav117/pymtl,Abhinav117/pymtl,Abhinav117/pymtl