print_with_compare re-implementation of show_datatype is bad

[vtjnash]

julia> Base.print_with_compare(stdout, Int, Int, :a)
Int64{}

julia> Int64{}
ERROR: TypeError: in Type{...} expression, expected UnionAll, got Type{Int64}

observed while trying to decipher this printing (from #36573):

julia> Base.showerror(stdout, MethodError(convert, (Type{Tuple{Tuple{Int64,Int64},Int64}}, Tuple{Int64,Int64,Int64})))
MethodError: Cannot `convert` an object of type 
  Type{Tuple{Int64,Int64{},Int64}} to an object of type 
  Type{Tuple{Tuple{Int64,Int64},Int64{}}}

This code perhaps shouldn't be dispatching on type in this way, since it should probably be calling the normal show logic here.