Typescript - Incorrectly inferring 'never'

If you are absolutely sure that a has a value there, than you can put the ! after the variable

let a: number | null = null;
[1].forEach(() => {
  a = 1;
});

if (a !== null)
  a!.toFixed(); //

I would not use null thought but undefined, so no need to use !

let a: number | undefined;
[1].forEach(() => {
  a = 1;
});

if (a) {
  a.toFixed(); // No problem here
}

Also as recommendation use !== not !=

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