Fix bug in rocprof-compute parsing (#1664)

Were not handling the case where the eval result is None e.g. some
columns have a peak value, but it is unused, so we use 'None', which
evaluates to the None object.

Return empty string in this case.

projects/rocprofiler-compute/src/utils/parser.py

@@ -346,7 +346,7 @@ class MetricEvaluator:
                 local_expr_context,
             )
 
-            if np.isnan(eval_result).any():
+            if eval_result is None or np.isnan(eval_result).any():
                 return ""
             else:
                 return eval_result