Find the error in the code.
Difficulty: Hard😤

function processArray(arr) {
    let result = [];
    
    arr.forEach(item => {
        if (item != '') { 
            result.push(item);
        } else if (typeof item === 'number') { 
            result.push(item * 2);
        }
    });

    return result;
}

let data = [1, '', 2, 3, '', 5, null, undefined, 'hello'];

console.log(processArray(data));