尝试使用mongodb创建新用户时出现e11000重复密钥错误

当我试图创建一个用户E11000重复密钥错误集合：rajTech时，我遇到了这个错误。用户索引：isAdmin_1 dup密钥：{isAdmin:false}

我的用户模式是

import mongoose from 'mongoose'

const userSchema = new mongoose.Schema(
    {
        name: {type: String, required: true},
        email: {type: String, required: true, unique: true},
        password: {type: String, required: true},
        isAdmin: {type: Boolean, default: false, required: true, unique: true},
        
    },
    {
        timestamps:true
    }
)
const User = mongoose.model('User', userSchema)
export default User

这是我的职责

userRouter.post(
    '/signup',
    expressAsyncHandler(async (req, res) => {
        const newUser = new User({
            name: req.body.name,
            email: req.body.email,
            password: bcrypt.hashSync(req.body.password)
        })
        const user = await newUser.save()
        res.send({
            _id: user._id,
            name: user.name,
            email: user.email,
            isAdmin: false,
            token: generateToken(user)
    })
    }))