Suggestion

🔍 Search Terms

This condition will always return true since this 'Promise<string | undefined>' is always defined.(2801) Did you forget to use 'await'?

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

When checking the inverted truthyness if something returned from an async function without calling await, it should warn you you forgot await. This works without inverting.

📃 Motivating Example

async function foo(): Promise<string | undefined> {
    return
}

const value = foo()
if (!value) { // <-- fails silently
    // ...
}

const awaitedValue = await foo()
if (awaitedValue) { // <-- Emits ts2801
    // ...
}

Playground

💻 Use Cases

In my use, I had a function that returned a User | undefined and I was doing something if there wasn't a user returned. Later, I made the function async and forgot to update this since it was failing silently.