[PL] trigger ConfigTree error checks early

ProcessLib/Process.h

@@ -150,6 +150,7 @@ private:
 		_rhs.reset(_global_setup.createVector(num_unknowns));
 		_linear_solver.reset(new typename GlobalSetup::LinearSolver(
 		    *_A, solver_name, _linear_solver_options.get()));
+		_linear_solver_options->checkAndInvalidate();
 	}
 
 	/// Computes and stores global matrix' sparsity pattern from given