Remarks

Placing one of the NPC tiles (Z1 - 3) in a level with its value in the tileset being undefined or set to none will simply result in nothing appearing at the location. Fortunately the game will not crash or present any other kinds of abstract behaviour.

Setting the NPCs movieclip or sound_id variables to invalid values will result in the game crashing when the level containing the NPC is entered. Futhermore, not includng any of these fields, including text, will also cause a crash. However, if any of these problems occur, the game will display a helpful error message making debugging such as issue relatively easy.

Inclusion of the the text field but leaving it like so: text = [] will lead to the game crashing when the NPC is interacted with; no error message is supplied in such instances.