setProvider function in fresh's `useState` won't set the provider variable in `const [provider, setProvider] = useState(null);`

I am making a Fresh app (which is a next-gen web framework that works with Deno). I have an island designed to connect to Metamask. This is the code:
Metamask.tsx:

/** @jsx h */
import { h } from "preact";
import { useState, useEffect } from "preact/hooks";
import { tw } from "@twind";

import { ethers, providers } from "ethers";

export default function Metamask() {
    const [connected, setConnected] = useState(true);
    const [provider, setProvider] = useState(null);
    useEffect(() => {
        async function checkConnection(provider) {
            const addresses = await provider.listAccounts();
            if (addresses.length) {
                setConnected(true);
            } else {
                setConnected(false);
            }
            console.log('useEffect ran')
        }
        const isProviderNull = new Promise((resolve, reject) => {
            if (provider == null) {
                resolve(true);
            }
            else {
                resolve(false);
            }
        })
        function switchSetProvidr() {
            isProviderNull.then(async (result) => {
                if (result) {
                    setProvider(new ethers.providers.Web3Provider(window.ethereum));
                    console.log(provider);
                    await checkConnection(provider);
                }
                else {
                    await checkConnection(provider);
                }
                console.log(result);
            })
        }
        switchSetProvidr()
    }, []);

    async function signIn() {
        try {
            const provider = new providers.Web3Provider(window.ethereum);
            const accounts = await provider.send("eth_requestAccounts", []);
            setConnected(true);
        } catch (err) {
            console.log("error: ", err);
        }
    }

    return (
        <header class={tw`bg-gray-900`}>
            <div class={tw`max-w-screen-xl px-4 mx-auto sm:px-6 lg:px-8`}>
                <div class={tw`flex items-center justify-between h-16`}>
                    <div class={tw`flex items-center gap-4`}>
                        <div class={tw`sm:gap-4 sm:flex`}>
                            {connected ? (
                                <div
                                    class={tw`px-5 py-2.5 text-sm font-medium text-white bg-blue-600 rounded-md shadow disabled:(bg-gray-800 border border-blue-600 opacity-50 cursor-not-allowed)`}>
                                    Connected
                                </div>
                            ) : (
                                <button
                                    onClick={signIn}
                                    class={tw`px-5 py-2.5 text-sm font-medium text-white bg-blue-600 rounded-md shadow disabled:(bg-gray-800 border border-blue-600 opacity-50 cursor-not-allowed)`}>
                                    Connect
                                </button>
                            )}
                        </div>
                    </div>
                </div>
            </div>
        </header>
    );
}

When I run this, the console looks like this:

So the problem is that setProvider(new ethers.providers.Web3Provider(window.ethereum)); isn't working. provider is still null. So how do I get setProvider to work?

Notice that I am importing "preact/hooks" for useState and useEffect.