Validate user-entered JSON in settings

[kylebarron]

It's easy for users to create invalid JSON in the settings menu. For example, the remote kernels setting should be an Array of objects. If you supply just a single object, like

{
    "name": "remote_name",
    "options": {
        "baseUrl": "http://localhost:8888",
        "token": ""
    }
}

then there's an uncaught error:

Uncaught (in promise) TypeError: this.props.items.slice is not a function
    at SelectListView.computeItems (/home/kyle/github/atom_dev/Hydrogen/node_modules/atom-select-list/src/select-list-view.js:281:44)
    at SelectListView.update (/home/kyle/github/atom_dev/Hydrogen/node_modules/atom-select-list/src/select-list-view.js:174:12)
    at WSKernelPicker.<anonymous> (/home/kyle/.atom/packages/Hydrogen/lib/ws-kernel-picker.js:97:40)
    at Generator.next (<anonymous>)
    at step (/home/kyle/github/atom_dev/Hydrogen/lib/ws-kernel-picker.js:9:273)
    at /home/kyle/github/atom_dev/Hydrogen/lib/ws-kernel-picker.js:9:443
    at new Promise (<anonymous>)
    at WSKernelPicker.<anonymous> (/home/kyle/github/atom_dev/Hydrogen/lib/ws-kernel-picker.js:9:99)
    at Object.connectToWSKernel (/home/kyle/github/atom_dev/Hydrogen/lib/main.js:580:25)
    at HTMLElement.hydrogenConnectToRemoteKernel (/home/kyle/github/atom_dev/Hydrogen/lib/main.js:117:57)
    at CommandRegistry.handleCommandEvent (/usr/share/atom/resources/app/static/<embedded>:11:349858)
    at Object.didConfirmSelection (/usr/share/atom/resources/app/static/<embedded>:11:692740)
    at SelectListView.confirmSelection (/usr/share/atom/resources/app/static/<embedded>:11:858030)
    at HTMLDivElement.core:confirm (/usr/share/atom/resources/app/static/<embedded>:11:852909)
    at CommandRegistry.handleCommandEvent (/usr/share/atom/resources/app/static/<embedded>:11:349858)
    at KeymapManager.t.exports.KeymapManager.dispatchCommandEvent (/usr/share/atom/resources/app/static/<embedded>:11:1230399)
    at KeymapManager.t.exports.KeymapManager.handleKeyboardEvent (/usr/share/atom/resources/app/static/<embedded>:11:1226533)
    at WindowEventHandler.handleDocumentKeyEvent (/usr/share/atom/resources/app/static/<embedded>:11:285037)

it seems that it would be helpful to head off errors like this by validating the schema of input when it changes.

Try Joi

[kunalznk]

i can fix this can u assign it to me