cm: encode empty Lists as []

Author: ydnar

cm/list.go

@@ -65,9 +65,8 @@ func (l list[T]) Len() uintptr {
 
 // MarshalJSON implements json.Marshaler.
 func (l list[T]) MarshalJSON() ([]byte, error) {
-	if l.data == nil {
-		// This cannot return nullLiteral because the caller can mutate the slice.
-		return []byte("null"), nil
+	if l.len == 0 {
+		return []byte("[]"), nil
 	}
 
 	s := l.Slice()

cm/list_test.go

@@ -39,8 +39,8 @@ func TestListMarshalJSON(t *testing.T) {
 			w:    newListEncoder(``, []float64{float64(math.NaN())}, true),
 		},
 		{
-			name: "null",
-			w:    newListEncoder[string](`null`, nil, false),
+			name: "nil",
+			w:    newListEncoder[string](`[]`, nil, false),
 		},
 		{
 			name: "empty",