Check for Proxy before using it

src/Main.js

@@ -29,12 +29,14 @@ export default {
       observer = new Observer(connection, opts)
       Vue.prototype.$socket = observer.WebSocket
     }
+    const hasProxy = typeof Proxy !== 'undefined' && typeof Proxy === 'function' && /native code/.test(Proxy.toString())
 
     Vue.mixin({
       created () {
         let vm = this
         let sockets = this.$options['sockets']
 
+        if (hasProxy) {
           this.$options.sockets = new Proxy({}, {
             set (target, key, value) {
               Emitter.addListener(key, value, vm)
@@ -47,14 +49,17 @@ export default {
               return true
             }
           })
-
           if (sockets) {
             Object.keys(sockets).forEach((key) => {
               this.$options.sockets[key] = sockets[key]
             })
           }
+        } else {
+          Object.seal(this.$options.sockets)
+        }
       },
       beforeDestroy () {
+        if (hasProxy) {
           let sockets = this.$options['sockets']
 
           if (sockets) {
@@ -63,6 +68,7 @@ export default {
             })
           }
         }
+      }
     })
   }
 }