Standalone 'apptron build' app fails with 'write |1: file already closed'

[gmlewis]

I'm running on a Mac M2 Max with Sonoma 14.0.
I followed the steps in this video: https://youtu.be/XU-vrmA7j4U
and "apptron run" worked great.

However, if I run "apptron build", it builds fine and says:

building demo-01 ...
done! [103ms]

but when I run it with ./demo-01, it pauses for approximately 10 seconds, then dumps hundreds of lines of identical output (without ever popping up any new window):

2023/11/09 21:54:59 write |1: file already closed
2023/11/09 21:54:59 write |1: file already closed
...

and finally exits back to the terminal prompt.