src: fulfill Maybe contract in InlineDecoder

Use an empty/nothing `Maybe<>` to indicate a pending exception.

PR-URL: #25140
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/string_bytes.h

@@ -42,7 +42,7 @@ class StringBytes {
       enum encoding enc = ParseEncoding(env->isolate(), encoding, _default);
       if (!StringBytes::IsValidString(string, enc)) {
         env->ThrowTypeError("Bad input string");
-        return v8::Just(false);
+        return v8::Nothing<bool>();
       }
 
       size_t storage;