Unable to register ts-node when the baseUrl compiler option is not set

[ianyong]

Describe the bug

Since TypeScript 4.1, the paths compiler option can be used without the baseUrl compiler option. However, the ConfigurationLoader assumes that the baseUrl option is set when the paths option is set when MikroORM's useTsNode flag in package.json is set to true:

mikro-orm/packages/core/src/utils/ConfigurationLoader.ts

Lines 135 to 148 in b0ecd21

	const { options } = tsNode.register({
	project: tsConfigPath,
	transpileOnly: true,
	compilerOptions: {
	module: 'commonjs',
	},
	}).config;
	if (Object.entries(options?.paths ?? {}).length > 0) {
	Utils.requireFrom('tsconfig-paths', tsConfigPath).register({
	baseUrl: options.baseUrl,
	paths: options.paths,
	});
	}

In the above code snippet, the register function from tsconfig-paths expects baseUrl to be a string. When the baseUrl compiler option is not set, the error below occurs.

Stack trace

TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received undefined
    at new NodeError (node:internal/errors:399:5)
    at validateString (node:internal/validators:163:11)
    at Object.isAbsolute (node:path:1157:5)
    at configLoader (/Users/ianyong/<redacted>/node_modules/.pnpm/tsconfig-paths@4.1.0/node_modules/tsconfig-paths/src/config-loader.ts:50:34)
    at Object.register (/Users/ianyong/<redacted>/node_modules/.pnpm/tsconfig-paths@4.1.0/node_modules/tsconfig-paths/src/register.ts:79:42)
    at Function.registerTsNode (/Users/ianyong/<redacted>/node_modules/.pnpm/@mikro-orm+core@5.7.12_@mikro-orm+migrations@5.7.12_@mikro-orm+postgresql@5.7.12_@mikro-orm+seeder@5.7.12/node_modules/@mikro-orm/core/utils/ConfigurationLoader.js:118:71)
    at Function.configure (/Users/ianyong/<redacted>/node_modules/.pnpm/@mikro-orm+cli@5.7.12_@mikro-orm+migrations@5.7.12_@mikro-orm+postgresql@5.7.12_@mikro-orm+seeder@5.7.12_pg@8.11.0/node_modules/@mikro-orm/cli/CLIConfigurator.js:29:61)
    at async /Users/ianyong/<redacted>/node_modules/.pnpm/@mikro-orm+cli@5.7.12_@mikro-orm+migrations@5.7.12_@mikro-orm+postgresql@5.7.12_@mikro-orm+seeder@5.7.12_pg@8.11.0/node_modules/@mikro-orm/cli/cli.js:13:18 {
  code: 'ERR_INVALID_ARG_TYPE'
}

To Reproduce
Steps to reproduce the behavior:

1. Enable the useTsNode flag in package.json.
2. Set the paths compiler option but not the baseUrl compiler option in tsconfig.json.
3. Run any command that makes use of ts-node, such as mikro-orm migration:fresh.

Expected behavior

When baseUrl is not specified, it should default to '.' instead of throwing an error.

Additional context

The expected behaviour described above is effectively the same approach taken by the tsconfig-paths library itself when reading directly from a tsconfig.json file which does not have the baseUrl compiler option specified (dividab/tsconfig-paths#208). The reason why I believe this issue should be fixed within MikroORM and not upstream is because in this case, MikroORM is not respecting the interface of the register method by passing in an argument of type string | undefined when string is expected.

Versions

Dependency	Version
node	18.16.0
typescript	5.0.3
mikro-orm	5.7.12