So, I made a fake goal for tinkering with the API apitinkeringdomore, intended to never derail by requiring 1 unit per year, with an extra saftey buffer of 99999999999 days (or however many nines the field let me enter), and logging a datapoint with 999999 events.
It looks like that breaks things.
and the Gallery:
Note that the goal error is also displaying the character literals \n instead of newlines…
I would assume that what happened was the large number of safe days overflowed whatever datatype your parse the field into.