In MicroPico 4.x, COM connection fails with USB UART adaptor to RPi Pico

[RotatingLlama]

What are the steps to reproduce this issue?

1. Connect to a Pico by its UART pins via a USB COM adaptor, instead of using its USB port
2. Launch VS Code with MicroPico 4.x

What happens?

Extension fails to connect to Pico.

What were you expecting to happen?

Successful connection. REPL prompt appears. Remote filesystem appears.

Any logs, error output, etc?

From MicroPico log:

2025-06-03 20:00:54.909 [error] [PicoRemoteFileSystem] stat: unexpected result type for /
2025-06-03 20:00:54.909 [error] [PicoRemoteFileSystem] stat: unexpected result type for /
2025-06-03 20:00:54.910 [error] [PicoRemoteFileSystem] readFile: unexpected result type

From Extension Host log:

2025-06-03 20:32:41.949 [error] Error: Error entering raw repl
	at n (c:\Users\Tom\.vscode\extensions\paulober.pico-w-go-4.0.0-win32-x64\dist\extension.cjs:1:78636)
	at onwriteError (node:internal/streams/writable:605:3)
	at onwrite (node:internal/streams/writable:649:7)
	at c:\Users\Tom\.vscode\extensions\paulober.pico-w-go-4.0.0-win32-x64\dist\extension.cjs:1:58484

Any other comments?

Thonny connects OK, and so does mpremote. Going back to MicroPico v.3.8.4 fixes the problem. My boot.py:

from machine import UART, Pin
from os import dupterm
uart.init( baudrate=115200, bits=8, parity=None, stop=1, tx=Pin(0), rx=Pin(1) )
dupterm(uart)
print('boot.py')

Which version of MicroPico are you using?

3.8.4 - works as expected
4.0.0 - bug exists
4.2.2 - bug exists

Support info

Version: 1.100.3 (user setup)
Commit: 258e40fedc6cb8edf399a463ce3a9d32e7e1f6f3
Date: 2025-06-02T13:30:54.273Z
Electron: 34.5.1
ElectronBuildId: 11369351
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.26100