More specific return type

Signed-off-by: Kamil Tekiela <tekiela246@gmail.com>

libraries/classes/Message.php

@@ -104,7 +104,7 @@ class Message implements Stringable
     /**
      * holds additional messages
      *
-     * @var    mixed[]
+     * @var    (string|Message)[]
      */
     protected array $addedMessages = [];
 
@@ -538,7 +538,7 @@ class Message implements Stringable
     /**
      * return all added messages
      *
-     * @return mixed[]
+     * @return (string|Message)[]
      */
     public function getAddedMessages(): array
     {

psalm-baseline.xml

@@ -7642,15 +7642,11 @@
       <code><![CDATA[$this->params]]></code>
     </MixedArgument>
     <MixedAssignment>
-      <code>$addMessage</code>
       <code>$val</code>
     </MixedAssignment>
     <MixedInferredReturnType>
       <code>string</code>
     </MixedInferredReturnType>
-    <MixedOperand>
-      <code>$addMessage</code>
-    </MixedOperand>
     <MixedReturnStatement>
       <code><![CDATA[self::$level[$this->getNumber()]]]></code>
     </MixedReturnStatement>