Make default layer size 16-bit (#15286)

Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>

layouts/community/ergodox/osx_fr/keymap.c

@@ -141,7 +141,7 @@ LAYOUT_ergodox(
 // Runs constantly in the background, in a loop.
 void matrix_scan_user(void) {
 
-    uint8_t layer = biton32(layer_state);
+    uint8_t layer = get_highest_layer(layer_state);
 
     ergodox_board_led_off();
     ergodox_right_led_1_off();