Fix bug

src/parser3.h

@@ -1134,7 +1134,7 @@ inline PRESERVE_NONE WeaselJsonStatus n_string2(Parser3 *self, char *buf,
     }
     MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
   default:
-    __builtin_unreachable();
+    [[unlikely]] return WeaselJson_REJECT;
   }
 }