Node: Crash in module_wrap.cc with malformed loader

[targos]

loader.mjs:

export function transformSource() {
  return {
    source: {
      boom: true,
    },
  };
}

test.mjs:

import fs from 'fs';

> node --loader ./loader.mjs test.mjs
C:\Program Files\PowerShell\7\pwsh.exe[28872]: c:\ws\src\module_wrap.cc:131: Assertion `args[2]->IsString()' failed.

[Himself65]

C:\Users\Himself65\Desktop\github\test\33441>node --trace-warnings --loader ./module.mjs test.mjs
(node:27700) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
    at emitExperimentalWarning (internal/util.js:183:11)
    at Object.initializeLoader (internal/process/esm_loader.js:52:3)
    at runMainESM (internal/modules/run_main.js:45:20)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:68:5)
    at internal/main/run_main_module.js:17:47
  - node  --trace-warnings --loader ./module.mjs test.mjs[27700]: c:\ws\src\module_wrap.cc:131: Assertion `args[2]->IsString()' failed.
 1: 00007FF6BD16CEDF v8::internal::wasm::DisjointAllocationPool::~DisjointAllocationPool+74383
 2: 00007FF6BD115A16 v8::base::CPU::has_sse+62326
 3: 00007FF6BD115D91 v8::base::CPU::has_sse+63217
 4: 00007FF6BD146F27 node::Stop+15447
 5: 00007FF6BD925E3F v8::internal::Builtins::builtin_handle+330191
 6: 00007FF6BD92506C v8::internal::Builtins::builtin_handle+326652
 7: 00007FF6BD9256B2 v8::internal::Builtins::builtin_handle+328258
 8: 00007FF6BD925513 v8::internal::Builtins::builtin_handle+327843
 9: 00007FF6BDA0356D v8::internal::SetupIsolateDelegate::SetupHeap+466093
10: 00007FF6BD9974F1 v8::internal::SetupIsolateDelegate::SetupHeap+23601
11: 00007FF6BDA7FACB v8::internal::SetupIsolateDelegate::SetupHeap+975371
12: 00007FF6BD99B708 v8::internal::SetupIsolateDelegate::SetupHeap+40520
13: 00007FF6BD9C8A00 v8::internal::SetupIsolateDelegate::SetupHeap+225600
14: 00007FF6BDA4455E v8::internal::SetupIsolateDelegate::SetupHeap+732318
15: 00007FF6BD9BB66D v8::internal::SetupIsolateDelegate::SetupHeap+171437
16: 00007FF6BD9991DC v8::internal::SetupIsolateDelegate::SetupHeap+31004
17: 00007FF6BD87CEAD v8::internal::Execution::CallWasm+1933
18: 00007FF6BD87CFBB v8::internal::Execution::CallWasm+2203
19: 00007FF6BD87DAFA v8::internal::Execution::TryCall+378
20: 00007FF6BD85E4F5 v8::internal::MicrotaskQueue::RunMicrotasks+501
21: 00007FF6BD85E250 v8::internal::MicrotaskQueue::PerformCheckpoint+32
22: 00007FF6BD18DC29 node::CallbackScope::~CallbackScope+777
23: 00007FF6BD18DFAD node::CallbackScope::~CallbackScope+1677
24: 00007FF6BD18618A v8::internal::compiler::Operator::EffectOutputCount+234
25: 00007FF6BD10CC15 v8::base::CPU::has_sse+25973
26: 00007FF6BD100E41 v8::internal::OrderedHashTable<v8::internal::OrderedHashSet,1>::NumberOfBucketsOffset+45297
27: 00007FF6BD1C1337 uv_timer_stop+775
28: 00007FF6BD1BDD3B uv_async_send+331
29: 00007FF6BD1BD4CC uv_loop_init+1228
30: 00007FF6BD1BD678 uv_run+216
31: 00007FF6BD0CFC95 EVP_CIPHER_CTX_buf_noconst+40117
32: 00007FF6BD142830 node::Start+288
33: 00007FF6BCFA66FC RC4_options+339452
34: 00007FF6BDEB782C v8::internal::compiler::RepresentationChanger::Uint32OverflowOperatorFor+156812
35: 00007FF9BB966FD4 BaseThreadInitThunk+20
36: 00007FF9BC91CEC1 RtlUserThreadStart+33

[devsnek]

this should fix it up:

diff --git a/lib/internal/modules/esm/translators.js b/lib/internal/modules/esm/translators.js
index a7252c1c99..a59e8f9373 100644
--- a/lib/internal/modules/esm/translators.js
+++ b/lib/internal/modules/esm/translators.js
@@ -85,7 +85,7 @@ translators.set('module', async function moduleStrategy(url) {
     source, { url, format: 'module' }, defaultTransformSource));
   maybeCacheSourceMap(url, source);
   debug(`Translating StandardModule ${url}`);
-  const module = new ModuleWrap(url, undefined, source, 0, 0);
+  const module = new ModuleWrap(url, undefined, `${source}`, 0, 0);
   moduleWrap.callbackMap.set(module, {
     initializeImportMeta,
     importModuleDynamically,

[Himself65]

32202 fixes this

now, it will output:

\node\Release\node.exe --loader ./module.mjs C:\Users\Himself65\Desktop\github\test\33441\test.mjs
(node:21912) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
internal/modules/run_main.js:54
    internalBinding('errors').triggerUncaughtException(
                              ^

TypeError [ERR_INVALID_RETURN_PROPERTY_VALUE]: Expected array buffer, or typed array to be returned for the "source" from the "transformSource" function but got instance of Object.
    at assertBufferSource (internal/modules/esm/translators.js:60:9)
    at stringify (internal/modules/esm/translators.js:70:3)
    at Loader.moduleStrategy (internal/modules/esm/translators.js:119:12)
    at async link (internal/modules/esm/module_job.js:41:21) {
  code: 'ERR_INVALID_RETURN_PROPERTY_VALUE'
}

Process finished with exit code 1

closing