Calls to ARKStepSetMaxNumSteps do not assign their return value to flag, yet AMREX_ALWAYS_ASSERT(flag == 0) follows. The assert checks a stale value from a previous API call.

Fixes Issue #5045

Summary

Additional background

Checklist

The proposed changes:

• fix a bug or incorrect behavior in AMReX
• add new capabilities to AMReX
• changes answers in the test suite to more than roundoff level
• are likely to significantly affect the results of downstream AMReX users
• include documentation in the code and/or rst files, if appropriate