Fix widget autoHeight related exception

[ranbena]

• Bug Fix

Description

Fixes #3857.

The error is due to 2 bugs in the autoHeight code:

1. When resizing a non-autoheight widget, it gets added as a removed widget.
   Fixed by filtering it out:

   remove = (id) => {
     if (!this.widgets[id]) {
       return;
     }

2. When detecting height change, already removed widgets aren't filtered out. Since removed widgets have a value of false, the array deconstruction generated the js error:
   

   redash/client/app/components/dashboards/AutoHeightController.js

   Lines 81 to 82 in b27df21

   	Object.keys(this.widgets).forEach((id) => {
   	const [getHeight, prevHeight] = this.widgets[id];

   
   Fixed by filtering it out:

   Object
      .keys(this.widgets)
      .filter(id => !!this.widgets[id])

Testing

The feature has e2e coverage so it's safe.