Update Tap Dance Example 4 (qmk#18138)

break statements are missing from the switch for both registering and unregistering key codes. Neither have a default: case either. The code as exists in the repository right now does not compile. It does with this changes.

docs/feature_tap_dance.md

@@ -332,7 +332,8 @@ void x_finished(qk_tap_dance_state_t *state, void *user_data) {
         // Last case is for fast typing. Assuming your key is `f`:
         // For example, when typing the word `buffer`, and you want to make sure that you send `ff` and not `Esc`.
         // In order to type `ff` when typing fast, the next character will have to be hit within the `TAPPING_TERM`, which by default is 200ms.
-        case TD_DOUBLE_SINGLE_TAP: tap_code(KC_X); register_code(KC_X);
+        case TD_DOUBLE_SINGLE_TAP: tap_code(KC_X); register_code(KC_X); break;
+        default: break;
     }
 }
 
@@ -341,8 +342,9 @@ void x_reset(qk_tap_dance_state_t *state, void *user_data) {
         case TD_SINGLE_TAP: unregister_code(KC_X); break;
         case TD_SINGLE_HOLD: unregister_code(KC_LCTL); break;
         case TD_DOUBLE_TAP: unregister_code(KC_ESC); break;
-        case TD_DOUBLE_HOLD: unregister_code(KC_LALT);
-        case TD_DOUBLE_SINGLE_TAP: unregister_code(KC_X);
+        case TD_DOUBLE_HOLD: unregister_code(KC_LALT); break;
+        case TD_DOUBLE_SINGLE_TAP: unregister_code(KC_X); break;
+        default: break;
     }
     xtap_state.state = TD_NONE;
 }