fix: bad encoding to hex

src/ws/connection.js

@@ -49,12 +49,12 @@ function Worker() {
 const buildKeepalivePayload = async () => {
   const { user } = AuthStore.getRawState();
   const payload = user && user.id ? user.id.toString() : "";
-  const signature = user.secret ? hmacSHA1(payload, user.secret) : null;
+  const signature = !!user.secret ? hmacSHA1(payload, user.secret) : null;
 
   return {
     event: "KEEPALIVE",
     payload,
-    sig: hex.stringify(signature),
+    sig: signature ? hex.stringify(signature) : null,
   };
 };