fix subject f string

streamlit-venv/lib/python3.10/site-packages/fontTools/feaLib/error.py

@@ -0,0 +1,22 @@
+class FeatureLibError(Exception):
+    def __init__(self, message, location):
+        Exception.__init__(self, message)
+        self.location = location
+
+    def __str__(self):
+        message = Exception.__str__(self)
+        if self.location:
+            return f"{self.location}: {message}"
+        else:
+            return message
+
+
+class IncludedFeaNotFound(FeatureLibError):
+    def __str__(self):
+        assert self.location is not None
+
+        message = (
+            "The following feature file should be included but cannot be found: "
+            f"{Exception.__str__(self)}"
+        )
+        return f"{self.location}: {message}"