refactor: cleanup formatting and unify string formatting code

models/FileMove.py

@@ -16,7 +16,7 @@ class FileMove:
             if not os.path.exists(self.intermediate):
                 os.rename(self.source, self.intermediate)
             else:
-                raise Exception("intermediate already exists", self)
+                raise Exception("intermediate already exists: {0}".format(self))
 
     def move_target(self, dry_run: bool = True):
         if dry_run:
@@ -30,4 +30,8 @@ class FileMove:
             if not os.path.exists(self.target):
                 os.rename(self.intermediate, self.target)
             else:
-                raise Exception("target already exists", self)
+                raise Exception("target already exists: {0}".format(self))
+
+    def __str__(self):
+        return "FileMove(source=\'{0}\', target=\'{1}\', intermediate=\'{2}\')" \
+            .format(self.source, self.target, self.intermediate)

models/TrackMeta.py

@@ -58,6 +58,3 @@ class TrackMeta:
         self.titlesort = titlesort
         self.tracknumber = tracknumber
         self.tracktotal = tracktotal
-
-
-

util/auto_str.py

 def auto_str(cls):
     def __str__(self):
-        return '%s(%s)' % (
+        return '{}({})'.format(
             type(self).__name__,
-            ', '.join('%s=%s' % item for item in vars(self).items())
+            ', '.join('{}={}'.format(*item) for item in vars(self).items())
         )
+
     cls.__str__ = __str__
     return cls

util/extract_numbers.py

@@ -5,6 +5,9 @@ def extract_numbers(tag: str) -> Tuple[Optional[str], Optional[str]]:
     number = None
     total = None
 
+    if tag is None:
+        return number, total
+
     split = str(tag).split("/")
     if len(split) >= 1:
         number = int(split[0])