Duplicate error message hides information from the user.

Please understand this is a minor issue.

I am adding a test field 'w' to an entity ( via the ui ) and get an error. The error is expected and i can resolve, but it exposes a little message issue (as below), the text of which is ambiguous to the root cause of the error.

There was a problem creating field w: The "string" plugin does not exist.

I have traced the problem to FieldStorageAddForm.php ( \Drupal\field_ui\Form\FieldStorageAddForm::submitForm() )

Looking at the comments, the code splits into 2 paths "//Create new field" and "//Re-use existing field"

this error message

drupal_set_message($this->t('There was a problem creating field %label: !message', array('%label' => $values['label'], '!message' => $e->getMessage())), 'error');

is used in both the cases and makes it difficult for me to identify which caused the error and hence get to the resolution.

So, in the event that the error is due to 'reusing' the field, rather than 'creating' it, I suggest an alteration to the message for a distinction.

[ so explicitly correct one of the message so that the difference is known as to whether the issue is caused when "creating" or "reusing" ]

drupal_set_message($this->t('There was a problem reusing field %label: !message', array('%label' => $values['label'], '!message' => $e->getMessage())), 'error');