librclone: allow empty string or null input instead of empty json object

librclone/librclone/librclone.go

@@ -88,10 +88,12 @@ func RPC(method string, input string) (output string, status int) {
 	}()
 
 	// create a buffer to capture the output
+	if input != "" {
 		err := json.NewDecoder(strings.NewReader(input)).Decode(&in)
 		if err != nil {
 			return writeError(method, in, fmt.Errorf("failed to read input JSON: %w", err), http.StatusBadRequest)
 		}
+	}
 
 	// Find the call
 	call := rc.Calls.Get(method)