Importing invalid filetypes now gives proper error messages

CURA-2883

cura/Settings/CuraContainerRegistry.py

@@ -210,7 +210,7 @@ class CuraContainerRegistry(ContainerRegistry):
                     return {"status": "ok", "message": catalog.i18nc("@info:status", "Successfully imported profile {0}", profile_or_list[0].getName())}
 
         # If it hasn't returned by now, none of the plugins loaded the profile successfully.
-        return {"status": "error", "message": catalog.i18nc("@info:status", "Profile {0} has an unknown file type.", file_name)}
+        return {"status": "error", "message": catalog.i18nc("@info:status", "Profile {0} has an unknown file type or is corrupted.", file_name)}
 
     def _configureProfile(self, profile, id_seed, new_name):
         profile.setReadOnly(False)

plugins/CuraProfileReader/CuraProfileReader.py

@@ -99,4 +99,6 @@ class CuraProfileReader(ProfileReader):
             return []
 
         filenames, outputs = profile_convert_funcs[0](serialized, profile_id)
+        if filenames is None and outputs is None:
+            return []
         return list(zip(outputs, filenames))

plugins/VersionUpgrade/VersionUpgrade21to22/Profile.py

@@ -5,6 +5,7 @@ import configparser #To read config files.
 import io #To write config files to strings as if they were files.
 
 import UM.VersionUpgrade
+from UM.Logger import Logger
 
 ##  Creates a new profile instance by parsing a serialised profile in version 1
 #   of the file format.
@@ -80,6 +81,7 @@ class Profile:
         import VersionUpgrade21to22 # Import here to prevent circular dependencies.
 
         if self._name == "Current settings":
+            Logger.log("w", "Unable to upgrade this profile. Skipping it.")
             return None, None #Can't upgrade these, because the new current profile needs to specify the definition ID and the old file only had the machine instance, not the definition.
 
         config = configparser.ConfigParser(interpolation = None)