diagnostics: True suggestion in error message

timeloopfe/common/backend_calls.py

@@ -153,7 +153,9 @@ def _parse_output(
         f"Timeloop {m} failed with return code {result}. Please check the output files "
         f"in {output_dir} for more information. To debug, you can edit the file "
         f"{os.path.join(output_dir, 'parsed-processed-input.yaml')} and run "
-        f"tl {m} {os.path.join(output_dir, 'parsed-processed-input.yaml')} to see the error."
+        f"tl {m} {os.path.join(output_dir, 'parsed-processed-input.yaml')} to see the error. "
+        f"If you're running the mapper and Timeloop can't find a vaild mapping, try setting "
+        f"'diagnostics: true' in the mapper input specification."
     )
 
     if result != 0: