Can't narrow {} to Record<string, any> using custom type guards/assertions - Post 4.8 beta regression

[dragomirtitian]

Bug Report

🔎 Search Terms

narrow {} custom type guard type assertion Record<string,any>

🕗 Version & Regression Information

• This changed between versions 4.8.0-dev.20220715 and 4.8.0-dev.20220716

⏯ Playground Link

Playground Link

💻 Code

function isObject(o: unknown): o is Record<string, any> {
    return true;
}

function assertObject(o: unknown): asserts o is Record<string, any> {
    
}

let value: {} = null!;
if(isObject(value)) {
    value.aything // error since 4.8.0-dev.20220716
}

assertObject(value)

value.aything // error since 4.8.0-dev.20220716

🙁 Actual behavior

value.aything is an error even after the custom type assertions/guards. value still apears as {} instead of Record<string, any>

🙂 Expected behavior

Should be able to access value.aything after custom assertion/guard and value should be of type Record<string, any> in if, after assertion.

[MartinJohns]

This sounds like a duplicate of #49988.

[dragomirtitian]

Fixed.