Merge pull request #2451 from scottARob/iss_2450-return-str-when-none…

…-on-encoding

FastHttpUser: encoding return str when response is empty

locust/contrib/fasthttp.py

@@ -463,7 +463,7 @@ def text(self) -> Optional[str]:
             if self.headers is None:
                 self.encoding = "utf-8"
             else:
-                self.encoding = get_encoding_from_headers(self.headers)
+                self.encoding = get_encoding_from_headers(self.headers) or ""
         return str(self.content, self.encoding, errors="replace")
 
     @property