Uncaught TypeError: Cannot read property 'onDisconnect' of undefined

```
buffer-chrome-embed.js:29 Uncaught TypeError: Cannot read property 'onDisconnect' of undefined
connectToExtension @ buffer-chrome-embed.js:29
setTimeout (async)reconnectToExtension @ buffer-chrome-embed.js:14
EventImpl.dispatch_ @ extensions::event_bindings:371
dispatchOnDisconnect @ extensions::messaging:306
```
