Add missing PETSc/SLEPc error checks

[Siya-05]

Summary

Refers to #4045.

Add missing PETSc/SLEPc error checks for previously unchecked calls in fem, la, and nls.

Changes

• add checks for VecCreateNest in cpp/dolfinx/fem/petsc.cpp
• add missing PETSc error checks in cpp/dolfinx/la/petsc.cpp using the existing CHECK_ERROR(...) pattern
• add checks for selected SLEPc/PETSc calls in cpp/dolfinx/la/slepc.cpp
• add checks for VecNorm, VecAXPY, and MatCreateVecs in cpp/dolfinx/nls/NewtonSolver.cpp

Notes

• follow the existing per-file error-handling style
• do not change behavior except to check and report PETSc/SLEPc errors consistently

[jhale]

This needs doing, but it would be good to drop into Slack #development to discuss precisely how it should be done.

[Siya-05]

Sorry for being late on this,

While looking through the remaining PETSc-related files, I noticed that NewtonSolver.cpp and slepc.cpp also have a few unchecked PETSc calls. Unlike la/petsc.cpp, they don't have access to the local CHECK_ERROR macro.

So I updated the PETSc error handling in la/petsc.cpp by replacing remaining manual if (ierr != 0) petsc::error(...).

[jhale]

I still see a number of if (ierr != 0) petsc::error(...) which need to be replaced with CHECK_ERROR.

[jhale]

If the macro is an issue, just reimplement the macro where you need it?

[Siya-05]

@jhale I've reimplemented the CHECK_ERROR macro where needed and updated the remaining manual PETSc/SLEPc error checks to use it consistently.

When you have a chance, could you please take another look? Thanks!