问题一：

Application HelloWorld_o1 has not been registered.

Hint: This error often happens when you're running the packager (local dev server) from a wrong folder. For example you have multiple apps and the packager is still running for the app you were working on before.
If this is the case,simply kill the old packager instance (e.g. close the packager terminal window) and start the packager in the correct app folder (e.g. cd into app folder and run 'npm start').

This error can also happen due to a require() error during initialization or failure to call AppRegistry.registerComponent.

**重点内容**
runApplication
    AppRegistry.js:151:6
__callFunction
    MessageQueue.js:244:47
<unknown>
    MessageQueue.js:108:26
guard
    MessageQueue.js:46:4
callFunctionReturnFlushedQueue
    MessageQueue.js:107:10

这是一个项目在多个终端运行打开了，解决办法是关闭所有终端重新打开一个终端重新运行该项目