diff --git a/PyTeX/format/config.py b/PyTeX/format/config.py
index 2e5bbcb..7562382 100644
--- a/PyTeX/format/config.py
+++ b/PyTeX/format/config.py
@@ -36,17 +36,19 @@ class Config:
     @classmethod
     def from_json(cls, content: Union[Path, Dict]):
         if isinstance(content, Path):
-            with open(content, 'r') as config:
-                content: Dict = json.load(config)
+            with open(content, 'r') as file:
+                json_content: Dict = json.load(file)
+        else:
+            json_content = content
         config = cls()
-        config.set_from_json(content)
+        config.set_from_json(json_content)
         return config
 
     @classmethod
     def from_yaml(cls, path: Path):
-        with open(path, 'r') as config:
-            path: Dict = yaml.safe_load(config)
-        return cls.from_json(path)
+        with open(path, 'r') as file:
+            json_content: Dict = yaml.safe_load(file)
+        return cls.from_json(json_content)
 
     def set_from_json(self, content: Optional[Dict]):
         raise NotImplementedError
diff --git a/PyTeX/format/tex_formatter.py b/PyTeX/format/tex_formatter.py
index fe5ccea..fe0fdb9 100644
--- a/PyTeX/format/tex_formatter.py
+++ b/PyTeX/format/tex_formatter.py
@@ -56,8 +56,8 @@ class TexFormatter(PyTeXFormatter):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self._macros: List[Macro] = []
-        self._line_stream: LineStream = None
-        self._output_file: TextIO = None
+        self._line_stream: Optional[LineStream] = None
+        self._output_file: Optional[TextIO] = None
 
     @property
     def line_stream(self) -> LineStream: