Update( ) fails if the user is interacting with the plot

[Watashiku]

Hi !

I use an heatmap to represent large datasets. After plotly_relayout events I download and process data (asynchronous, can take some time), then display them. However Plotly will return an undefined error from a promise if the update is done while dragging. I used a setTimeout in the codepen to copy the behavior of my program.

CodePen : https://codepen.io/watashiku/pen/pKJJNW?editors=1010
Error message :

plotly-latest.js:128472 Uncaught TypeError: Cannot read property 'length' of undefined
    at exports.drawData (VM750 plotly-latest.js:128472)
    at Object.lib.syncOrAsync (VM750 plotly-latest.js:119125)
    at relayout (VM750 plotly-latest.js:125433)
    at Object.exports.call (VM750 plotly-latest.js:153164)
    at VM750 plotly-latest.js:133800
    at Object.lib.syncOrAsync (VM750 plotly-latest.js:119125)
    at Object.dragTail [as doneFn] (VM750 plotly-latest.js:133798)
    at HTMLDocument.onDone (VM750 plotly-latest.js:102144)

Steps to reproduce : drag the plot once, then quickly start dragging again and hold it one second - the bug appears if you are dragging during the update triggered by the previous drag.

It creates two major problems :

• The plot will be "locked" on the screen : panning or zooming will not affect the plot (only the axes in the background),
• There is no plotly_afterplot event triggered by Plotly which means there is no way for me to tell the user that the plot is ready nor somehow handling the situation by myself (and the error cannot be catched outside of Plotly due to the way it is raise I think?).

Notes :

• When the bug happens clicking on the graph fixes it
• The behavior is similar for react, restyle and addtrace. It does not appear with plot (but this creates traces for every relayout)

[alexcjohnson]

Looks like the same root issue as #2643, or perhaps #2644. Regardless we clearly need some better solutions for updating a plot that the user may already be interacting with...

[Watashiku]

Yes those issues are very similar !

Is there a way for us to detect when the issue happens until it is fixed ? I did not find a catch case on the promise that fails. The only thing I found is catching all the document.windows error and look for an undefined one 😕

[jacobq]

Is this the same problem I am running into in this example?
https://codepen.io/jacobq_/pen/KexEEB

Simply clicking somewhere on the plot area while it's running generates errors like these:

(I usually see '0' when clicking and 'length' when dragging / making a zoom-in box)

[julesair]

I experience the same error when dragging the plot in my ExtJs application too quickly. The traces are locked, only the axes change. After clicking once on the plot area, it works again as intended.

[wenBunny]

Friends, I still have this issue...in version 1.41.3. Exact same error, reproduction steps and workaround (click graph and back).

[etpinard]

Merged into #3305