Live preview error with grid field search parameter and IS_EMPTY

[robinsowell]

So grid fields let you use a search parameter like the channel entry tag.

{blog_image search:caption="=blog"}
					<figure>
						<img src="{blog_image:image}" alt="{blog_image:caption:attr_safe}">
						<figcaption>{blog_image:caption}</figcaption>
					</figure>
				{/blog_image}

This works- frontend and in live preview. But if you so:

{blog_image search:caption="IS_EMPTY"}

It works on the frontend, but the preview gives you an error:

Warning
Undefined array key "col_id_12!="""
ee/legacy/models/grid_model.php, line 509