Calculating risk associated with a collar trade

A friend asked me a question about risk and collar trades. I provided an answer, but then started doubting if the answer was correct.

Example:

BTO 100 shares of XYZ stock
BTO 1 Jan 2020 $100 PUT
STO 1 Jan 2020 $100 CALL
The entire transaction was done for $100 debit.

I said that if the position is held until expiry, there would be not risk (not counting fees).

Is that correct or did I miss something?