Cannot read property 'isDatetime' of undefined

[doc-l]

I think you can reproduce this if you rename a facet when it is in a plot

Uncaught TypeError: Cannot read property 'isDatetime' of undefined
    at initChart (http://nlesc.github.io/spot/app.js:4:27283)
    at update (http://nlesc.github.io/spot/app.js:4:29075)
    at child.update (http://nlesc.github.io/spot/app.js:5:244)
    at child.<anonymous> (http://nlesc.github.io/spot/app.js:4:17620)
    at Object.triggerEvents (http://nlesc.github.io/spot/app.js:8:14517)
    at child.trigger (http://nlesc.github.io/spot/app.js:8:13138)
    at child.filter.getData (http://nlesc.github.io/spot/app.js:5:19090)
    at http://nlesc.github.io/spot/app.js:5:19495
    at Array.forEach (native)
    at child.Collection.(anonymous function) (http://nlesc.github.io/spot/app.js:8:2713)

[jiskattema]

Fixed by disabling facet editing for datasets that are in use.
However, the current setup with a dataview that combines datasets needs more explanation / documentation.