removed return value declaration from getProviderHandler (#181)

* removed return value declaration from getProviderHandler

since prividerHandler can be null this will throw an exception in case of null

* Update src/Event/Newsletter/Mailchimp/TemplateExportResolveProviderHandlerEvent.php

Co-authored-by: Christian Fasching <[email protected]>

Co-authored-by: Christian Fasching <[email protected]>

Author: MercuryKojo

src/Event/Newsletter/Mailchimp/TemplateExportResolveProviderHandlerEvent.php

@@ -49,7 +49,7 @@ public function getName()
     /**
      * @return Mailchimp|null
      */
-    public function getProviderHandler(): Mailchimp
+    public function getProviderHandler(): ?Mailchimp
     {
         return $this->providerHandler;
     }