[Bug Report] GasOptics computation fails with reduced g-point sets and a subset of gases.

[RobertPincus]

Describe the bug
GasOptics computation fails with reduced g-point sets and a subset of gases.

To Reproduce
Steps to reproduce the behavior
Set the conditional guarding test_rfmip_lw128_reduced_gases in pyrte_rrtmgp/tests/test_rfmip_clear_sky.py to True and run this test.

Expected behavior
This test should run to completion. We'll check correctness separately :-)

Software Versions:

• OS:MacOS 15.5 (but I expect all)
• Version (or most recent commit hash) of RTE+RRTMGP: ddf9288