See [https://github.com/nim-lang/Nim/issues/14564](https://github.com/nim-lang/Nim/issues/14564).
TL;DR: As the error suggests, you don't have any IO operations or timers in progress so the event loop has nothing to do and so you get this error (if you didn't get this error your program would busy wait, leading to 100% cpu usage) What is your bigger program? What does it do? If you're not doing any IO operations then you might not need to be using futures at all.
