__get() method can't have a fixed return type because of the field() method also returning several types.

Author: patacra

src/Supporting/FileMakerRelation.php

@@ -209,7 +209,7 @@ public function count(): int
      * @return FileMakerRelation|string|null
      * @ignore
      */
-    public function __get($key): FileMakerRelation
+    public function __get($key)
     {
         return $this->field($key);
     }