Add functionality for converting exceptions to HTTP responses

[MAILPOET-2900]

lib/API/JSON/ErrorHandler.php

@@ -0,0 +1,27 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\API\JSON;
+
+use MailPoet\Exception;
+use MailPoet\HttpAwareException;
+use MailPoet\WP\Functions as WPFunctions;
+
+class ErrorHandler {
+  /** @var string[] */
+  private $defaultErrors;
+
+  public function __construct(WPFunctions $wp) {
+    $this->defaultErrors = [
+      Error::UNKNOWN => $wp->__('An unknown error occurred.', 'mailpoet'),
+    ];
+  }
+
+  public function convertToResponse(\Throwable $e): ErrorResponse {
+    if ($e instanceof Exception) {
+      $errors = $e->getErrors() ?: $this->defaultErrors;
+      $statusCode = $e instanceof HttpAwareException ? $e->getHttpStatusCode() : Response::STATUS_UNKNOWN;
+      return new ErrorResponse($errors, [], $statusCode);
+    }
+    return new ErrorResponse($this->defaultErrors, [], Response::STATUS_UNKNOWN);
+  }
+}