I am working on custom implementation of Promise.allSettled in NodeJs. When I implement using Promise.then it works perfectly. But when I implement using Async/Await it throw the error.

[UnhandledPromiseRejection: This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason “Failed”.] {
code: ‘ERR_UNHANDLED_REJECTION’
}.

function myCustomAllSettled2(promises){
    return new Promise(async (resolve, reject) => {
        try{
            let completedCount = 0
            let results = []
            for(let i=0; i<promises.length; i++){
                try{
                    let result = await promises[i]
                    results[i] = {"status": "fulfilled", "value": result}
                }
                catch(ex){
                    results[i] = {"status": "rejected", "reason": ex.message || ex}
                }
                finally{
                    completedCount += 1
                    if(completedCount === promises.length){
                        resolve(results)
                    }
                }
            }  
        }
        catch(ex){
            reject(ex)
        }    
    })
};

function myCustomAllSettled(promises){
    return new Promise((resolve, reject) => {
        let completedCount = 0
        let results = []
        for(let i=0; i<promises.length; i++){
            promises[i].then(result => {
                results[i] = {"status": "fulfilled", "value": result}
            }).catch(ex => {
                results[i] = {"status": "rejected", "reason": ex.message || ex}
            }).finally(() => {
                completedCount += 1
                if(completedCount === promises.length){
                    resolve(results)
                }
            })
        }        
    })
};

(async()=>{
    try{
        let s = new Promise((resolve, reject) => {
            setTimeout(() => {
                resolve('Success')
            }, 400)
        })
        
        let f = new Promise((resolve, reject) => {
            setTimeout(() => {
                reject('Failed')
            }, 300)
        })

        let promises = [s,f]
        //This works well
        myCustomAllSettled(promises).then(results => {
            results.forEach(result => {
                if(result.status === 'fulfilled'){
                    console.log('Success : ' , result.value)
                }
                else{
                    console.log('Failed : ' , result.reason)
                }
            });
        })

        let s2 = new Promise((resolve, reject) => {
            setTimeout(() => {
                resolve('Success')
            }, 400)
        })
        
        let f2 = new Promise((resolve, reject) => {
            setTimeout(() => {
                reject('Failed')
            }, 300)
        })
        let promises2 = [s2,f2]
        //This throws error
        let results = await myCustomAllSettled2(promises2)
        results.forEach(result => {
            if(result.status === 'fulfilled'){
                console.log('Success : ' , result.value)
            }
            else{
                console.log('Failed : ' , result.reason)
            }
        });
    }
    catch(ex){
        console.log(ex)
    }
})();

I tried implementing using Promise.then and it worked. But When I try to implement using async/await it throws error.