Unhandled error when adding or removing columns in Text Columns

[jasmussen]

As reported by @mhenrylucero in #219 (comment):

So I just updated the Gutenberg plugin, and tried to mess with columns in it. I created a new post and added a column layout block, and tried to increase it using the slider. Every time I try to do this, it displays the error: "This block has encountered an error and cannot be previewed."

Steps to Reproduce (for bugs)

1. Insert a Text Columns block
2. Open block settings sidebar
3. Resize to fewer or more columns

You get an unhandled error.

[mtias]

Duplicate of #3709.