Error hiding and redisplaying multiple histograms

[acdoussan]

Uncaught (in promise) TypeError: Cannot read property 'length' of undefined
    at Object.calc (plotly-latest.js:168006)
    at calci (plotly-latest.js:148106)
    at Object.plots.doCalcdata (plotly-latest.js:148130)
    at exports.plot (plotly-latest.js:123908)
    at Object.lib.syncOrAsync (plotly-latest.js:119125)
    at Object.restyle (plotly-latest.js:125048)
    at EventEmitter.<anonymous> (pen.js:69)
    at EventEmitter.emit (plotly-latest.js:29592)
    at HTMLDivElement.plotObj.emit (plotly-latest.js:117770)
    at plotly-latest.js:125052

https://codepen.io/anon/pen/oyZMOG

To trigger this error, on the line chart, first, disable trace A by clicking on it in the legend. Then, on the line chart, disable trace B by clicking on it in the legend. Finally, on the line chart, re-enable trace B by clicking on it in the legend. The shown stack trace is produced in the JavaScript console and trace B is not updated on the histogram. I have found more than one way to trigger this error but this is the most easily reproducible.

Also, after triggering this error, moving the mouse over the histogram throws continuous errors.

Is there a supported way for syncing traces on different charts? This was the best that I could come up with.

@rahul0705

[alexcjohnson]

Confirmed - thanks! This doesn't seem to have anything to do with syncing the charts though - the same thing happens if you just click the legend items the same way on the histogram, or a similar multi-trace histogram plot all by itself.

[alexcjohnson]

in fact any recalc after hiding the first of several histogram traces - click to hide A and then doubleclick the plot to autorange and the same happens.

[alexcjohnson]

Closed by #2724 - would be closed automatically when this fix hits master but first we're going to publish it with a patch off its own branch