TypeScript Version: 3.9.0 (Nightly)

Search Terms: T | (() => T), T & Function

Code

type Initializer<T> = T | (() => T)
// type Initializer<T> = T extends any ? (T | (() => T)) : never

function correct<T>(arg: Initializer<T>) {
    return typeof arg === 'function' ? arg() : arg // error
}

Line 2 provides a workaround for this.
More info on stackoverflow.

Expected behavior: no errors

Actual behavior: This expression is not callable. Not all constituents of type '(() => T) | (T & Function)' are callable. Type 'T & Function' has no call signatures.

Playground Link: here.

Related Issues: none