isErr

isErr(value)

A function that takes an unknown value and narrows it to Err<unknown>.

data-first

isErr(ok(true)); //=> false
isErr(err(false)); //=> true
isErr(true); //=> false

data-last

pipe(ok(true), isErr()); //=> false
pipe(err(false), isErr()); //=> true
pipe(true, isErr()); //=> false