fix(web-llm): fix infinite loading when local model cache is invalid

Author: tonyhu-012

utils/rpc/background-fns.ts

@@ -565,6 +565,7 @@ function initWebLLMEngine(model: WebLLMSupportedModel) {
         },
       })
       port.postMessage({ type: 'ready' })
+      port.disconnect()
     })
     return { portName }
   }