Add API exception handling and error response

[MAILPOET-4135]

mailpoet/lib/Automation/API/API.php

@@ -2,8 +2,10 @@
 
 namespace MailPoet\Automation\API;
 
+use MailPoet\Automation\Exceptions\Exception;
 use MailPoet\Automation\WordPress;
 use ReflectionClass;
+use Throwable;
 
 class API {
   private const PREFIX = 'mailpoet/v1/automation';
@@ -45,9 +47,19 @@ class API {
     $this->wordPress->registerRestRoute(self::PREFIX, $route, [
       'methods' => strtoupper($method),
       'callback' => function ($wpRequest) use ($endpoint, $method) {
-        $request = new Request($wpRequest);
+        try {
-        return $this->endpointFactory->createEndpoint($endpoint)->$method($request);
+          $request = new Request($wpRequest);
+          return $this->endpointFactory->createEndpoint($endpoint)->$method($request);
+        } catch (Throwable $e) {
+          return $this->convertToErrorResponse($e);
+        }
       },
     ]);
   }
+
+  private function convertToErrorResponse(Throwable $e): ErrorResponse {
+    return $e instanceof Exception
+      ? new ErrorResponse($e->getStatusCode(), $e->getMessage(), $e->getErrorCode())
+      : new ErrorResponse(500, 'An unknown error occurred.', 'mailpoet_automation_unknown_error');
+  }
 }

mailpoet/lib/Automation/API/ErrorResponse.php

@@ -0,0 +1,18 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Automation\API;
+
+class ErrorResponse extends Response {
+  public function __construct(
+    int $status,
+    string $message,
+    string $code
+  ) {
+    parent::__construct(null, $status);
+    $this->set_data([
+      'code' => $code,
+      'message' => $message,
+      'data' => ['status' => $status],
+    ]);
+  }
+}