Further improve error recovery

implementations/racket/preserves/main.rkt

@@ -486,6 +486,7 @@
               [(px #px#"^#base64\\{" (list _))
                (read-base64-binary '())]
               [_
+               (read-char i)
                (parse-error "Invalid preserve value")])]
        [#\: (read-char i) (parse-error "Unexpected key/value separator between items")]
        [_ (read-raw-symbol '())])))