Don't use null to represent state

8/10/26

Instead of saying:

 /**
   * Id of the env currently being switched to (null when idle).
   */
  targetEnvId?: string | null;

Using null as a value and then needing a comment to explain it, I think you should use a value:

const targetEnv: { type: 'env', id: string } | { type: 'idle' }
	= { type: 'idle' }

Or you could use a symbol:

const IdleEnv = Symbol();
 
const targetEnv: string | typeof IdleEnv = IdleEnv

But, I think all of this maybe suggests there is a larger “state” object that could be constructed to prevent invalid states.