Long running process exits with IOSelectorsException

[PMunch]

I have a program which runs for a long time, every once in a time sending something over MQTT. Recently I got a crash with this error message:

  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(2022) waitFor
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(1711) poll
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(1452) runOnce
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(269) processPendingCallbacks
  /home/peter/.nimble/pkgs2/nmqtt-1.0.5-e9b66114ab9f39559f01e200164bfff921c0c8f3/nmqtt.nim(1094) runConnect (Async)
  /home/peter/.nimble/pkgs2/nmqtt-1.0.5-e9b66114ab9f39559f01e200164bfff921c0c8f3/nmqtt.nim(1066) connectBroker (Async)
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncnet.nim(296) dial (Async)
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(1902) dial
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(1868) tryNextAddrInfo
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(1733) createAsyncNativeSocket
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/asyncdispatch.nim(1247) register
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/ioselects/ioselectors_epoll.nim(136) registerHandle
  /home/peter/.choosenim/toolchains/nim-2.0.0/lib/pure/selectors.nim(287) raiseIOSelectorsError
Exception message: Maximum number of descriptors is exhausted!
 [IOSelectorsException]

Might be something else in my program which leaks descriptors, but figured I'd report it here first since the error was triggered in nmqtt. The MqttContext lives for the lifetime of the program, and the messages are sent wrapped in a start/disconnect construct (but not in a try/finally one).