Specifying formatConfig.separator in structure.json crashes qri-desktop's structure component

[hbruch]

Currently, qri-desktop crashes when structure.json has formatConfig.separator defined and structure component is selected.

FormatConfigFSI.tsx:101 Uncaught TypeError: Cannot read property 'type' of undefined
    at FormatConfigFSI.tsx:101
    at Array.map (<anonymous>)
    at FormatConfigFSI (FormatConfigFSI.tsx:100)
    at FormatConfigFSI (react-hot-loader.development.js:827)
    at renderWithHooks (react-dom.development.js:16241)
    at updateFunctionComponent (react-dom.development.js:18328)
    at beginWork$1 (react-dom.development.js:20151)
    at HTMLUnknownElement.callCallback (react-dom.development.js:336)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:385)
    at invokeGuardedCallback (react-dom.development.js:440)

Support for separator currently is not implemented. Yelling ;-)