selectedpoints doesn't work from Plotly.update for scattergl

[kevinoe]

If you do a box select (and lasso?) in a scatter plot, you can no longer update the selected points via update. Also, if the dragmode STARTS as select, selectedpoints fails entirely.

For this example:
https://codepen.io/ks_openeye/pen/gvLrxR

1. Notice the second point is already selected
2. Switch to box select.
3. Select the last point
4. Click the button - notice it fails to select the point with index 1

For this example (dragmode == 'select' to start)
https://codepen.io/ks_openeye/pen/bLBpKM

1. Notice no points render
2. The console throws an error (scene.unselectBatch is null):

plotly-latest.js:180868 Uncaught (in promise) TypeError: Cannot read property '0' of null
    at plotly-latest.js:180868
    at Array.map (<anonymous>)
    at Object.plot (plotly-latest.js:180820)
    at plotOne (plotly-latest.js:135422)
    at Object.exports.plot (plotly-latest.js:135394)
    at drawData (plotly-latest.js:125636)
    at Object.lib.syncOrAsync (plotly-latest.js:120901)
    at Plotly.plot (plotly-latest.js:125691)
    at Object.lib.syncOrAsync (plotly-latest.js:120901)
    at Object.update (plotly-latest.js:127454)
(anonymous) @ plotly-latest.js:180868
plot @ plotly-latest.js:180820
plotOne @ plotly-latest.js:135422
exports.plot @ plotly-latest.js:135394
drawData @ plotly-latest.js:125636
lib.syncOrAsync @ plotly-latest.js:120901
Plotly.plot @ plotly-latest.js:125691
lib.syncOrAsync @ plotly-latest.js:120901
update @ plotly-latest.js:127454
updateSelected @ pen.js:25
(anonymous) @ pen.js:30
Promise resolved (async)
(anonymous) @ pen.js:29

[etpinard]

This appears to be fixed in the current master - most likely by @dfcreative 's #2311

---

@kevinoe We'll release 1.34.0 with a fix for this issue in the next few hours, so I'll close this ticket.

Please reopen an issue if ever 1.34.0 still shows the problem.