SQLSTATE[42S22]: Column not found: 1054 Unknown column 'feeds_item.entity_type' in 'on clause'

This fixes the issue - can this be committed?

I encountered with same problem. We can also remove operator element (by default =). Correct patch was attached.

I'd like to test the patch. When does this problem occur?

This is occur when you are using relationship for the Feeds item. I've attached an image for check.

@alan-io1 Thanks for posting the image! That was very helpful.

I tested the patch. The issue seems to only arise when the feeds_item table is joined twice, for example when you want to show guids or import dates of both nodes and the attached taxonomy terms. Or, when using Commerce, guids/import dates from both the product displays as well as the products.
However, I didn't get the error message from the original poster (maybe due to changes in the Views module?).

I looked up in the Views documentation what that "extra" actually means (so I can verify if the patch in #4 fixes the issue in the right way). This from the Views advanced help:

extra

Either a string that's directly added, or an array of items. Each item is, itself, an array:

table

table should not be set in most cases, as it would be filled with the right table alias. Set it to NULL if you want to use a formular in "field"

field

Field or formula, therein "%alias" can be used to reference the right table.

operator

Similar to filters, this is the operator, such as >, <, =, etc. Defaults to = or IN.

value

Must be set. If an array, operator will be defaulted to IN.

numeric

If true, the value will not be surrounded in quotes, and %d will be used for its placeholder.

I also tested if "extra" could be omitted completely, but that resulted into duplicate rows in my case, so the patch does the right thing.

RTBC.