[Bug]: 'level' parameter of winston.createLogger() no longer accepts type 'string', breaks ability to set log level via environment variable

The problem

When using environment variables to set ‘level’ property of winston.createLogger({ level: ... }), VSCode displays the following error: Type 'string' is not assignable to type 'level | undefined'.

It appears that in v3.5.0 the type for the level parameter was changes from 'string | undefined' (as in v3.4.0 and prior) to 'level | undefined' where ‘level’ is a type defined by winston as type level = "debug" | "error" | "warn" | "info" | "http" | "verbose" | "silly"

Even when defining the type for the environment variable to winston.level this type error still occurs:

import { level } from 'winston'
declare namespace NodeJS {
  interface ProcessEnv {
    LOG_LEVEL: level
  }
}

then

import { createLogger } from 'winston'
const logger = createLogger({
  level: process.env.LOG_LEVEL  // error occurs here
})

Current workaround

import level and assert the environment variable as the level type.

import { createLogger, type level } from 'winston'

const logger = createLogger({
  level: process.env.LOG_LEVEL as level
})

What version of Winston presents the issue?

3.5.0

What version of Node are you using?

14.17.3

If this worked in a previous version of Winston, which was it?

3.4.0

Minimum Working Example

No response

Additional information

No response

[carboneater]

So I opened #2048 to apply generics most everywhere to solve the overly strict types.

However, for all the flexibility & ease of use I’ve worked into that one, it is still not globally without breaking changes. (Typescript users using custom loglevels will need to tweak their type annotations.)

Going forward, I would strongly advise reverting #1896 and publishing it as 3.5.1.

#1896 & #2048 should be released as part of a new major version, if only because they can break TypeScript code using Winston.

[wbt]

Going forward, I would strongly advise reverting #1896 and publishing it as 3.5.1.

This has been done. Apologies for missing the impact of adding those types on custom levels! Also tests involving custom levels which would’ve caught that earlier are welcome.