Don't try to call doneFnCompleted when it isn't set

[etpinard]

fixes #3754

@plotly/plotly_js here's the hotfix, we should investigate why our tests didn't catch this though.

[archmoj]

💃

[antoinerg]

Thanks for the fix @etpinard !!! 💃

[etpinard]

Thanks for the review! I'm still trying to figure why our select_test.js are eating up console errors.

I'll release this fix later this afternoon.

[etpinard]

9856354 🔒 down the fix. I was hoping to find a better to look for errors inside promise chains (I even tried bringing back Lib.promiseError cc #1705), but to no avail.

Oh well, I hope you think this will be good enough for 1.47.1.

[etpinard]

Merging this thing in. 1.47.1 will be out in ~20 minutes