PETSc error code checking #4045
Description
We do not perform consistent error code checking of the PETSc error codes returned by function invocations. Not dealing with the returned error code will become a compiler warning in the future, ref https://gitlab.com/petsc/petsc/-/blob/main/include/petscsystypes.h#L54-57.
Verifiable by configuring PETSc with --with-strict-petscerrorcode ([[no-discard]] marking of PetscErrorCode) and building with -Werror.