Great point 流年! We can use a microtask implementation that uses MutationObserver like nanotask, we’d just need to change apply from:

const apply = (value, state) => { …

to:

const apply = (value, state) => queue(() => { …

Another microtask difference is new Promise(resolve => {throw new Error();}). In browsers, this actually throws the error on next tick, Nancy doesn’t. Instead of:

try {
    executor(resolve, reject);
} catch (error) {
    reject(error);
}

We can do:

try {
    executor(resolve, reject);
} catch (error) {
    reject(error);
    queue(() => {
        throw error;
    });
}