I just had the game crash;
I have installed it via the itch.io app on Windows 10. Analytics is turned on.
I don't know which fight (my stats were 10, 10, 2; so... seventh?) I was on but my pidgeon "Pombo" had been upgraded twice in the strength direction (+40% on attacks) and I had just bought the Wyvern wing for him. Upon entering the fight, the first time the Fridgeon (I think? This is the first time I've played this game!) hit me the game jammed with the Fridgeon sprite overlaying Pombo's sprite - the "loading" blue circle cursor came up, twice, each for a few seconds, and then the window closed.
I hope this helps... it's a shame as I seemed to be having a good run!
Good game <3