env var substitutions break if the variable isn't set

[aminnaggar]

I'm submitting a...

[ ] Regression 
[X] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request

Current behavior

If you use Environment Variable Substitution by setting ignoreEnvironmentVariableSubstitution to false and the environment variable is not set it throws an error crashing the app.

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project/node_modules/nest-typed-config/lib/loader/file-loader.ts:90
      throw new Error(
            ^
Error: Environment variable is not set for variable name: 'NODE_ENV'
    at replace (project/node_modules/nest-typed-config/lib/loader/file-loader.ts:90:13)
    at String.replace (<anonymous>)
    at placeholderResolver (project/node_modules/nest-typed-config/lib/loader/file-loader.ts:100:19)
    at project/node_modules/nest-typed-config/lib/loader/file-loader.ts:147:30
    at Function.getRawConfig (project/node_modules/nest-typed-config/lib/typed-config.module.ts:76:12)
    at Function.forRoot (project/node_modules/nest-typed-config/lib/typed-config.module.ts:21:28)
    at Object../src/app.module.ts (project/dist/main.js:79:51)
    at __webpack_require__ (project/dist/main.js:937:42)
    at Object../src/main.ts (project/dist/main.js:700:22)
    at __webpack_require__ (project/dist/main.js:937:42)
No errors found.

Expected behavior

returning an undefined without throwing would be fantastic

Minimal reproduction of the problem with instructions

# .env.yml
testEnvs: ${NODE_ENV}

// in config schema
import { IsOptional, IsString } from 'class-validator';

export class Config {
  @IsString()
  @IsOptional()
  public readonly testEnvs?: string;
}

// in  app.module.ts module imports
TypedConfigModule.forRoot({
  schema: Config,
  load: fileLoader({
    ignoreEnvironmentVariableSubstitution: false,
  }),
  isGlobal: true,
}),

What is the motivation / use case for changing the behavior?

It would be better to respect the config schema, and allow optional fields to be treated as optional.

Environment

Nest version: 9.1.1

 
For Tooling issues:
- Node version: v18.8.0  
- Platform:  Linux Ubuntu

Others:

[Nikaple]

In order to avoid breaking changes, I'd suggest make this feature opt-in by adding another optional property to FileLoaderOptions, such as allowUndefinedEnvironmentVariables. PRs are welcome.

[aminnaggar]

Lovely. Thank you!

[github-actions[bot]]

:tada: This issue has been resolved in version 2.4.6 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: