Refactor error handling internally to follow RFC7807 (#362)

* Refactor error handling internally to follow RFC7807

* style fixes

app/Exceptions/Unauthenticated.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Exceptions;
+
+class Unauthenticated extends HttpException
+{
+    public function __construct()
+    {
+        parent::__construct(
+            401,
+            'User not authenticated'
+        );
+    }
+
+    /**
+     * Return the RFC 7807 error type (without the URL root)
+     */
+    public function getErrorType(): string
+    {
+        return 'unauthenticated';
+    }
+
+    /**
+     * Get the detailed error string
+     */
+    public function getErrorDetails(): string
+    {
+        return $this->getMessage();
+    }
+
+    /**
+     * Return an array with the error details, merged with the RFC7807 response
+     */
+    public function getErrorMetadata(): array
+    {
+        return [];
+    }
+}