errors with --experimental-loader trigger unhandled rejections in core

[targos]

$ node --experimental-modules --experimental-loader i-dont-exist test.mjs
(node:480349) ExperimentalWarning: The ESM module loader is experimental.
(node:480349) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
(node:480349) UnhandledPromiseRejectionWarning: Error: Cannot find package 'i-dont-exist' imported from /home/mzasso/test/m/
 at Loader.resolve [as _resolve] (internal/modules/esm/default_resolve.js:84:13)
 at Loader.resolve (internal/modules/esm/loader.js:74:33)
 at Loader.getModuleJob (internal/modules/esm/loader.js:148:40)
 at Loader.import (internal/modules/esm/loader.js:132:28)
 at internal/process/esm_loader.js:60:31
 at Object.initializeLoader (internal/process/esm_loader.js:64:5)
 at runMainESM (internal/bootstrap/pre_execution.js:480:20)
 at Function.Module.runMain (internal/modules/cjs/loader.js:1049:5)
 at internal/main/run_main_module.js:16:11
(node:480349) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:480349) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

$ node --experimental-modules --experimental-loader ./i-have-syntax-error.mjs test.mjs
(node:480438) ExperimentalWarning: The ESM module loader is experimental.
(node:480438) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
(node:480438) UnhandledPromiseRejectionWarning: SyntaxError: Unexpected end of input
 at Loader.moduleStrategy (internal/modules/esm/translators.js:84:18)
 at async link (internal/modules/esm/module_job.js:36:21)
(node:480438) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:480438) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[guybedford]

Great to see these, thanks.

It seems like the issue is that the promise catch handler at https://github.com/nodejs/node/blob/master/lib/internal/bootstrap/pre_execution.js#L484 should be moved up one level to also be able to catch the initializeLoader errors the same way.

[targos]

Fix: #30219