Error and traceback "Task exception wasn't retrieved" with uasyncio v2 on MicroPython 1.19.1

[jamesquilty]

Hi everyone, I'm hoping that someone will be able to help with a uasyncio v2 (fast_io 0.26) error I received when trying to run my existing code on MicroPython 1.19.1 (nightly). An async function will execute raise RuntimeError(...) when there's a problem and on 1.19.1 that causes the following to be printed to the console:

Task exception wasn't retrieved
future: <Task> coro= <generator object 'wrapped' at ...>
Traceback (most recent call last):
  File "uasyncio/core.py", line 1, in run_until_complete
  File "src/lib/asyn.py", line 483, in wrapped
  File "src/drivers/sdi12.py", line 134, in read_sensor
RuntimeError: Unable to take measurement reading

and execution to halt without returning to the REPL, i.e. the ESP32 hangs, requiring manual intervention (Ctrl-C).

I'm rather confused that an error + traceback are thrown on 1.19.1 when the code functions as intended on 1.14: no traceback and the RuntimeError is passed up the call chain to main.py where it's caught by an except clause, logged, and execution resumes.

Perhaps there's a clue at the top of the traceback where it states File "uasyncio/core.py", ... because the v2 fast_io file should be src/lib/uasyncio/core.py, similar to src/lib/asyn.py in the traceback? Preferring modules in the filesystem over frozen bytecode is set in the very first lines of main.py by changing the module search path:

import sys

if len(sys.path) > 0 and sys.path[0] == "":
    sys.path.append(sys.path.pop(0))

Can someone tell me whether my guess is indeed the source of the error... and, if so, how to make MicroPython 1.19.1 use the v2 fast_io module src/lib/uasyncio/core.py instead of the built-in v3 version?

[I'm happy to post the relevant code, I just didn't want to complicate the initial post with potential irrelevancies.]