TsConfig: flatten type errors. "Advanced Type" errors currently often unreadable.

[SephReed]

Search Terms

"Type error read"
"type errors unreadable"

Suggestion

Type checking, and type definitions errors could me made significantly easier to debug by flattening/boiling down the type definitions to something more resembling what developers think of them as.

1. This first example shows the kind of errors I run into in actual development. It's totally unreadable.

2. This second example shows the same effect

For this second example, it would be a lot more useful if instead it just showed what the type realistically is, and what it was missing. Ie:

Property "badProp" does not exist on type '{
  requestId: string;
  type: string;
  id?: string;
  createdAt?: Date;
  data?: string;
}'

This would be a really nice thing to add to tsconfig.

Use Cases

Almost 100% of the time one works with advanced types. Anything involving unions or (worst of all) utility types creates a wall of text.

Examples

// ts.config
{
  flattenTypesInMessaging: true
}

(I'll make a habit of posting all my most unreadable messages here)

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, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[RyanCavanaugh]

I really meant it in #35247 when I said we wanted a way to reproduce that error 😢

[SephReed]

I had made these at the same time, unsure of whether or not it was a vscode or typescript issue. The other one you linked was posted in vscode and moved here.