to reproduce:

git clone this repo, then

yarn install
# enable vscode auto attach or start this script with the vscode debugger:
yarn run reproduce

Expected output:

yarn reproduce

> @ reproduce /tmp/20.35
> node --import @swc-node/register/esm-register a/test.ts

this never happens
a
a
a
a

actual output

> @ reproduce /tmp/20.35
> node --import @swc-node/register/esm-register a/test.ts

Debugger listening on ws://127.0.0.1:43771/10e0e179-8b33-4a3a-bcbc-cc186e42e826
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
[hangs forever]

Same thing also happens with tsx not just swc-node fyi:

$ yarn add tsx
$ yarn tsx a/test.ts
Debugger listening on ws://127.0.0.1:36373/09fe9e25-e7e3-494e-87a5-1ea36cf52750
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
[hangs]

Same also happens with pnpm! not just yarn.

without vscode

Also happens when using chrome as debugger:

node --inspect --inspect-brk --import @swc-node/register/esm-register a/test.ts

Then open chrome to about://inspect and press "continue" on the breakpoint. it hangs. without libsql import it's fine