Avoid parsing active space when wavefunctions are used without proceeding to MRCI in molpro

[Lilachn91]

Parsing active space is needed before running an MRCI job in molpro. For a method type labeled as wavefunction (CC), ARC tries to run parse_active_space, but stops the whole job if SP was not in molpro.
Fixed to allow using wavefunctions without MRCI.

[Copilot]

Pull request overview

This PR fixes an issue where ARC would crash when running wavefunction methods (e.g., CCSD) using software other than Molpro. Active space parsing is only needed for MRCI jobs in Molpro, but the code was attempting to parse it for all wavefunction methods, causing failures when the output file wasn't from Molpro.

Changes:

• Modified parse_active_space to return None instead of raising an exception when the output file is not from Molpro
• Added a condition in post_sp_actions to only attempt active space parsing when it hasn't been set yet

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
arc/scheduler.py	Added condition to check if active space is None before parsing, avoiding redundant parsing and preventing errors
arc/parser/parser.py	Changed error handling to return None for non-Molpro files instead of raising InputError, allowing graceful handling of unsupported formats

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[calvinp0]

Looks great, just remove the commented out input Error code and then it's good to go