Invalid argument type causes "no such user operator" error

[philrz]

$ echo '{foo:"bar"} {foo:"baz"}' | super -c "count this" -
no such user operator: "count" at line 1, column 1:
count this
~~~~~~~~~~

$ echo '"foo"' | super -c 'search {}' -
no such user operator: "search" at line 1, column 1:
search {}
~~~~~~~~~

Details

Repro is with super commit 2ca4a33.

I happened to bump into the count variation when I was working on #6439, contemplating how the argument needs to be a record expression, so I went to see what happened if I provided an argument that wasn't one.

When reacting to the find, @nwt spotted the similar effect shown above with search, which expects a search expression argument, and a record expression is not a valid search expression.

[philrz]

I forgot to search for that error message before opening this issue, but it looks like there's two other existing issues where this error message surfaces in other contexts, in case anyone wants to look at them all together: #6238 #6304