Handle error and successfull responses from Pardot

Pardot does not send us back the validation errors. Its actually a edge case scenario, we expect admins to set whatever is set as required in pardot form to be set as required in webform too.

Smoothing out the edge cases is what separates this from the 'remote post' webform handler.

This is also a case that I was hoping to see us handle, unless Pardot makes it physically impossible.

There's a lot of things that can happen when submitting the data and only one of them is success. That's the edge case.

The contents of the log would depend on what information we're able to get back from Pardot. For example, in the event of an outage it may state that the site could not connect to Pardot or if Pardot rejects the submission because fields in the Webform don't match the form handler settings in Pardot, we will display as specific of information as is available to point someone to the problem quickly.

How does someone know they didn't match the forms? Weeks later someone notices they're not getting the marketing leads they expected? Then a developer has to get in there and debug things until they finally spot a simple mismatch?

What does Pardot send back? Can we give some hints when things fail?

+    // Log error message if status code is not 2xx.
+    if ($status_code < 200 || $status_code >= 300) {
+      $pardot_submission->addLog('An unexpected error occured while submitting data to Pardot');
+      $pardot_submission->setStatus(self::PARDOT_ERROR);
+      $pardot_submission->save();
+
+      return $pardot_submission;
+    }

Can't we get more specific than that? Does Pardot ever give 4xx responses? Which ones? Including the actual code would be a start. At least it might mean something to a developer. If it's a 5xx code we should log a message that says it was an error on Pardot's end. If it's 4xx it's not Pardot's problem and we can give something more helpful than "unexected error".

+  /**
+   * {@inheritdoc}
+   */
+  public function getStatus($status) {
+    return $entity->status->value;
+  }

$entity is undefined.

+  /**
+   * Provides the status of a pardot submission entity.
+   *
+   * @return string
+   *   The status string.
+   */
+  public function getStatus();

What is a status string?

+  /**
+   * Get response data.
+   *
+   * @param \Psr\Http\Message\ResponseInterface $response
+   *   The response returned by the remote server.
+   * @param \Drupal\webform_pardot\Entity\PardotSubmissionInterface $pardot_submission
+   *   The pardot submission entity.
+   *
+   * @return \Drupal\webform_pardot\Entity\PardotSubmissionInterface
+   *   Updated pardot submission entity.
+   */
+  private function processResponse(

"Get response data" and "@return Updated pardot submission entity" are conflicting.