silent error when using `,` in operations

consider the use of @orderby below. Look at the last example. Somehow, the syntax allows the use of , does not error, but provides an incorrect result.

julia> dd = DataFrame(a = [3, 1, 2], b = [5,4, 6])
3×2 DataFrame
 Row │ a      b     
     │ Int64  Int64 
─────┼──────────────
   1 │     3      5
   2 │     1      4
   3 │     2      6

# works correctly
julia> @orderby(dd, :a, :b)
3×2 DataFrame
 Row │ a      b     
     │ Int64  Int64 
─────┼──────────────
   1 │     1      4
   2 │     2      6
   3 │     3      5

# works correctly
julia> @orderby dd :a :b
3×2 DataFrame
 Row │ a      b     
     │ Int64  Int64 
─────┼──────────────
   1 │     1      4
   2 │     2      6
   3 │     3      5

# works silenty, but incorrect
julia> @orderby dd :a, :b
3×2 DataFrame
 Row │ a      b     
     │ Int64  Int64 
─────┼──────────────
   1 │     3      5
   2 │     1      4
   3 │     2      6

Start by reproducing the three @orderby examples from the issue, then inspect the @orderby macro implementation and its argument parsing. The comma-separated form should no longer silently return the unsorted result; add coverage for the examples and verify the intended error or consistent behavior.