Define control(bits) as "unset" for entities (minetest#11995)

doc/lua_api.txt

@@ -6716,18 +6716,21 @@ object you are working with still exists.
  `aux1`, `sneak`, `dig`, `place`, `LMB`, `RMB`, and `zoom`.
  * The fields `LMB` and `RMB` are equal to `dig` and `place` respectively,
  and exist only to preserve backwards compatibility.
+ * Returns an empty table `{}` if the object is not a player.
 * `get_player_control_bits()`: returns integer with bit packed player pressed
- keys. Bits:
- * 0 - up
- * 1 - down
- * 2 - left
- * 3 - right
- * 4 - jump
- * 5 - aux1
- * 6 - sneak
- * 7 - dig
- * 8 - place
- * 9 - zoom
+ keys.
+ * Bits:
+ * 0 - up
+ * 1 - down
+ * 2 - left
+ * 3 - right
+ * 4 - jump
+ * 5 - aux1
+ * 6 - sneak
+ * 7 - dig
+ * 8 - place
+ * 9 - zoom
+ * Returns `0` (no bits set) if the object is not a player.
 * `set_physics_override(override_table)`
  * `override_table` is a table with the following fields:
  * `speed`: multiplier to default walking speed value (default: `1`)

src/script/lua_api/l_object.cpp

@@ -1367,11 +1367,12 @@ int ObjectRef::l_get_player_control(lua_State *L)
  NO_MAP_LOCK_REQUIRED;
  ObjectRef *ref = checkobject(L, 1);
  RemotePlayer *player = getplayer(ref);
- if (player == nullptr)
- return 0;
 
- const PlayerControl &control = player->getPlayerControl();
  lua_newtable(L);
+ if (player == nullptr)
+ return 1;
+
+ const PlayerControl &control = player->getPlayerControl();
  lua_pushboolean(L, control.direction_keys & (1 << 0));
  lua_setfield(L, -2, "up");
  lua_pushboolean(L, control.direction_keys & (1 << 1));
@@ -1406,8 +1407,10 @@ int ObjectRef::l_get_player_control_bits(lua_State *L)
  NO_MAP_LOCK_REQUIRED;
  ObjectRef *ref = checkobject(L, 1);
  RemotePlayer *player = getplayer(ref);
- if (player == nullptr)
- return 0;
+ if (player == nullptr) {
+ lua_pushinteger(L, 0);
+ return 1;
+ }
 
  const auto &c = player->getPlayerControl();