async function getSpotifyTokens(
    clientId: string,
    clientSecret: string,
) {
    const tokenUrl = 'https://accounts.spotify.com/api/token'
    const authStr = `${clientId}:${clientSecret}`
    const b64AuthStr = Buffer.from(authStr).toString('base64')

    const headers = {
        Authorization: `Basic ${b64AuthStr}`,
        'Content-Type': 'application/x-www-form-urlencoded',
    }
    // const body = new URLSearchParams({
    //     grant_type: 'client_credentials',
    // })
    const body = 'grant_type=client_credentials'

    const response = await fetch(tokenUrl, {
        method: 'POST',
        headers,
        body,
    })

    if (!response.ok) {
        const errorText = await response.text()
        throw new Error(`Failed to get token: ${response.status} - ${errorText}`)
    }

    const tokens = (await response.json()) as ExtendedGetRefreshedAccessTokenResponse
    return tokens
}

async function getSpotifyTokens(
    clientId: string,
    clientSecret: string,
) {
    const tokenUrl = 'https://accounts.spotify.com/api/token'
    const authStr = `${clientId}:${clientSecret}`
    const b64AuthStr = Buffer.from(authStr).toString('base64')

    const headers = {
        Authorization: `Basic ${b64AuthStr}`,
        'Content-Type': 'application/x-www-form-urlencoded',
    }
    // const body = new URLSearchParams({
    //     grant_type: 'client_credentials',
    // })
    const body = 'grant_type=client_credentials'

    const response = await fetch(tokenUrl, {
        method: 'POST',
        headers,
        body,
    })

    if (!response.ok) {
        const errorText = await response.text()
        throw new Error(`Failed to get token: ${response.status} - ${errorText}`)
    }

    const tokens = (await response.json()) as ExtendedGetRefreshedAccessTokenResponse
    return tokens
}

const res = NextResponse.next()
res.cookies.set('cookie1', 'cookie1')
res.cookies.set('cookie2', 'cookie2')

const res = NextResponse.next()
res.cookies.set('cookie1', 'cookie1')
res.cookies.set('cookie2', 'cookie2')

<PayPalButtons
            createSubscription={async (data, actions) => {
                const res = await myFetch(
                    '/api/payment/create_subscription',
                    {
                        method: 'POST',
                    },
                )

                return actions.subscription
                    .create({
                        plan_id: res.id,
                    })
                    .then((orderId) => {
                        return orderId
                    })
            }}
            onApprove={async (data, actions) => {
                toast.success(`Subscription payment success! : ${data.subscriptionID}`)
            }}
        />

<PayPalButtons
            createSubscription={async (data, actions) => {
                const res = await myFetch(
                    '/api/payment/create_subscription',
                    {
                        method: 'POST',
                    },
                )

                return actions.subscription
                    .create({
                        plan_id: res.id,
                    })
                    .then((orderId) => {
                        return orderId
                    })
            }}
            onApprove={async (data, actions) => {
                toast.success(`Subscription payment success! : ${data.subscriptionID}`)
            }}
        />

const responseBody = JSON.stringify({
    accessToken: newAccessToken,
    refreshToken: newRefreshToken ?? '',
    expiresAt: Date.now() + 3600 * 1000,
})

return new Response(responseBody, {
    status: 200,
    headers: {
        'content-type': 'application/json',
    },
})

const responseBody = JSON.stringify({
    accessToken: newAccessToken,
    refreshToken: newRefreshToken ?? '',
    expiresAt: Date.now() + 3600 * 1000,
})

return new Response(responseBody, {
    status: 200,
    headers: {
        'content-type': 'application/json',
    },
})

    const { accessToken, expiresAt } = await fetch('/api/......', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({ refreshToken }),
    })
        .then((res) => {
            return res.json() // -<<<<<< It's ERRORING HERE
        })
        .then((d) => {
            return d
        })

    const { accessToken, expiresAt } = await fetch('/api/......', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({ refreshToken }),
    })
        .then((res) => {
            return res.json() // -<<<<<< It's ERRORING HERE
        })
        .then((d) => {
            return d
        })