fix a lot of errors (pylance)

iTunesDB.py

@@ -615,7 +615,7 @@ class ImageItemRecord(Record):
 
 def ArtworkDB(model, imagelist, base_id=0x40, cache_data=({}, {})):
     while isinstance(ImageFormats.get(model, None), str): model = ImageFormats[model]
-    if not model in ImageFormats: return None
+    if not model in ImageFormats: raise Exception
 
     format_cache, image_cache = cache_data
     formats = []
@@ -813,7 +813,7 @@ class DatabaseReader:
         return hh + self.f.read(size - 8)
 
     def __iter__(self): return self
-    def next(self):
+    def __next__(self):
         try: header = self._skip_header(Tags.IT)
         except (IOError, InvalidFormat): raise StopIteration
         data_size = struct.unpack('<L', header[8:12])[0] - len(header)