dotnet.wasm in node.js looks for module called 'a' and fails

[am11]

dotnet.wasm module does not load cleanly in the node.js environment. It complains about a missing package 'a'.

Repro:

$ node -v
v14.9.0

$ cat > test.mjs << EOF
import * as dotnet from '/Users/am11/.nuget/packages//microsoft.netcore.app.runtime.browser-wasm/5.0.0-rc.1.20425.18/runtimes/browser-wasm/native/dotnet.wasm';

const listMethods = subject => Object.getOwnPropertyNames(subject).filter(item => typeof subject[item] === 'function');

console.log(listMethods(dotnet));
EOF

$ node --experimental-modules --experimental-wasm-modules test.mjs
internal/process/esm_loader.js:74
    internalBinding('errors').triggerUncaughtException(
                              ^

Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'a' imported from /Users/am11/.nuget/packages/microsoft.netcore.app.runtime.browser-wasm/5.0.0-rc.1.20425.18/runtimes/browser-wasm/native/dotnet.wasm
    at packageResolve (internal/modules/esm/resolve.js:623:9)
    at moduleResolve (internal/modules/esm/resolve.js:664:18)
    at Loader.defaultResolve [as _resolve] (internal/modules/esm/resolve.js:778:11)
    at Loader.resolve (internal/modules/esm/loader.js:85:40)
    at Loader.getModuleJob (internal/modules/esm/loader.js:229:28)
    at ModuleWrap.<anonymous> (internal/modules/esm/module_job.js:51:40)
    at link (internal/modules/esm/module_job.js:50:36) {
  code: 'ERR_MODULE_NOT_FOUND'
}

Similar error about module 'a' occurs if we try WebAssembly.instantiate API:

$ cat > test2.mjs << EOF
import * as fs from 'fs';

const name = '/Users/am11/.nuget/packages//microsoft.netcore.app.runtime.browser-wasm/5.0.0-rc.1.20425.18/runtimes/browser-wasm/native/dotnet.wasm'
const bytes = fs.readFileSync(name);
const result =  WebAssembly.instantiate(bytes, {
  imports: { imported_func: arg => console.log(arg) }
}).catch(err => console.error(err));
EOF

$ node --experimental-modules --experimental-wasm-modules test2.mjs
[TypeError: WebAssembly.instantiate(): Import #0 module="a" error: module is not an object or function]

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

Tagging subscribers to this area: @CoffeeFlux
See info in area-owners.md if you want to be subscribed.

[marek-safar]

/cc @lewing

[am11]

Made some headway with Deno environment, instead of node.js, which offers a mature and non-experimental WASM support. Needed a build option to compile dotnet.js as an importable ES6 module: #41964.

[pavelsavara]

cc @Daniel-Genkin

[Daniel-Genkin]

@am11 I have been working on NodeJS support and got it working with the console sample.
Here it is for reference: #54640
Hope this is helpful

[am11]

Note that deno has since acquired utf-16le support, so sed hack in the PR description is not required anymore.

Opinion time:

1. I think we should consider naming the TargeOS as Server (consistent with the existing Browser) for node.js-like environments.
2. we should consider using JS modules unconditionally, since all environments that support wasm also support modules. (one less switch to test / worry about).