Add descriptive error message for pipelined loop duplicate parameters. I have been unable to reproduce this in a simple test so far.
Add descriptive error message for pipelined loop duplicate
parameters. I have been unable to reproduce this in a simple
test so far.

PiperOrigin-RevId: 469742134

google/xls,google/xls,google/xls,google/xls,google/xls,google/xls