[petsc-dev] the non-implemented case of PetscFEIntegrateResidual et al.

[Geoffrey Irving]

If a PetscFE object doesn't define integrateresidual, a call to
PetscFEIntegrateResidual silently does nothing.  Is this intended
behavior, or would it be better to complain similar to what happens
for an undefined matrix operation?  I ask because I'm about to add an
operation (PetscFEIntegrateScalars) which will initially only be
defined in basic mode.

Geoffrey