strictNullChecks produces unnecessary warnings on values which cannot be null

[willworkforhugs]

Bug Report

TypeScript reverts to more general type for a variable in an "or" comparison, producing "Object is possibly null" errors for variables which cannot be null at a given point in the code.

🔎 Search Terms

strictNullChecks

🕗 Version & Regression Information

let possibleObj: { someProp: boolean } | null;
possibleObj = { someProp: true };
const goodTest = possibleObj.someProp;
const badTest = true || possibleObj.someProp; // TS error "Object is possibly 'null'" when strictNullChecks === true

[nmain]

Duplicate of #26914, see also #31855

[willworkforhugs]

I don't understand why this would be intentional behavior. If checking is skipped/degraded on unreachable code for performance reasons, why not show no errors instead of incorrect errors?

[nmain]

I don't understand why this would be intentional behavior.

It's not; the linked issue is a bug and is still open.

[willworkforhugs]

It's not; the linked issue is a bug and is still open.

Got it, thanks. Saw lots of closed items there and mistook it as being shelved.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.