What real anti-pattern in your code is mixing types, and this has nothing to to with!!. Your function may receive anObject, aString, or anull, and had no notion of it. Another anti-pattern istypeof for such cases.

This is solved with anything from the Maybe monad to typing your data correctly:

constdata1={image:'bob.jpeg',error:null}constdata2={image:null,error:'Bob was not found'}constdata3={image:null,error:'Wrong authentication'}

In the real word,!! is not needed for other reasons.
!! converts from "falsy" tofalse, but it has no value by itself, as any JS context expecting a boolean, does it for you:

// if and ternaryif(2)'this is true'if('')'this is false'[]?'any array is true':newError('must never happen')0?'zero is not true':'it is false'

// logical operators2&&true// ==  true0||1||2//  == 1, obviouslytrue&&{}==true

So in your original codeif(image) is strictly equivalent toif(!!image).

TS would have helped here a lot.