This test exercises the panic in golang/go#59096: completing at a syntactic
type-assert expression was panicking because gopls was translating it into
a (malformed) selector expr.

-- go.mod --
module example.com

-- a/a.go --
package a

func _() {
	b.(foo) //@complete(re"b.()", B), diag("b", re"(undefined|undeclared name): b")
}

//@item(B, "B", "const (from \"example.com/b\")", "const")

-- b/b.go --
package b

const B = 0