RCP checker breaks if no RCP for batch size

[maanug-nv]

Currently, If the RCP checker is run on a results directory where the bs isn't present and cannot be interpolated, this causes it to error out with:
UnboundLocalError: local variable 'rcp_score_norm' referenced before assignment

This is because rcp_score_norm is not assigned in this case. Solution would be to add a default value, which would be ignored in this case anyway.