Don't show scary error message when saving custom file

CURA-9414

plugins/3MFWriter/ThreeMFWriter.py

@@ -275,14 +275,8 @@ class ThreeMFWriter(MeshWriter):
             package_id = package_manager.getMaterialFilePackageId(extruder.material.getFileName(), extruder.material.getMetaDataEntry("GUID"))
             package_data = package_manager.getInstalledPackageInfo(package_id)
 
+            # We failed to find the package for this material
             if not package_data:
-                # We failed to find the package for this material
-
-                message = Message(catalog.i18nc("@error:material",
-                                                "It was not possible to store material package information in project file: {material}. This project may not open correctly on other systems.".format(material=extruder.getName())),
-                                  title=catalog.i18nc("@info:title", "Failed to save material package information"),
-                                  message_type=Message.MessageType.WARNING)
-                message.show()
                 continue
 
             material_metadata = {"id": package_id,