Chart disappears in standalone slice

[duynguyenhoang]

As we implemented resizable panels in #12411

But this introduce issue with standalone slice, example http://localhost:8088/superset/explore/?form_data=%7B%22slice_id%22%3A%20185%7D&standalone=true

In standalone mode, chartWidth is set to undefined, which cause chart disappear

Expected results

Chart should be rendered properly in standalone url

Actual results

Chart disappears in standalone url

How to reproduce the bug

1. Go to standalone slice URL, example http://localhost:8088/superset/explore/?form_data=%7B%22slice_id%22%3A%20185%7D&standalone=true
2. See error, the page is empty.

Environment

(please complete the following information):

• superset version: mater
• python version: 3.8
• node.js version: v12.19.0

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

[duynguyenhoang]

I found the root cause, going to create PR couple of hours later.