undo fails with a filetype argument

[cosmicexplorer]

To repro:

Add a filetype filter with M-f (say, f, to search for only files). Running M-u to undo this causes an error. It may not raise an error, but the output may be blank -- in that case, try adding another filter (say, a regex filter with M-x), then undoing past the filetype filter. This leads to the following error message: Wrong number of arguments: (1 . 1), 0.