Man that's a shame, unfortunately this is a very old project of mine and I forgot most of its inner workings. Did it say that after building the last pieces of the ship or after the boss?
After building the last piece, that piece is named "001". The game show a message at the top: "¡Escape planet has no build function! Please report bug". I can continue playing but is a little disappointed this end. Anyway nice game and I will upload the gameplays to my youtube channel :) : https://www.youtube.com/channel/UCUaxwmBcLMriOxBXo-Gijtw
Hey it's been a billion years but I have finally found it, I thought the files had been deleted. Here it is , it's really short but at least you can get closure lol.