superfaktura_api: fix return values of get method

superfaktura/superfaktura_api.py

@@ -91,7 +91,10 @@ class SuperFakturaAPI:
                 return req.json()
             except requests.exceptions.JSONDecodeError as e:
                 raise SuperFakturaAPIException(
-                    f"Get status code: {req.status_code}; {req.content}; {e}"
+                    f"Unable to decode response as JSON; {req.content!r}; {e}"
+                )
+        raise SuperFakturaAPIException(
+            f"Get status code: {req.status_code}; {req.content!r}"
         )
 
     def post(self, endpoint: str, data: str, timeout: int = 5) -> Dict: