Error: Please pass numbers as strings or BigNumber objects to avoid precision errors

Question

let result = await instance.joinQuiz({
    from: accounts[1],
    value: web3.utils.toWei(10, "wei")
});

Answer 1

The signature of the toWei method is (can be found in the docs.

web3.utils.toWei(number [, unit])

number - String|BN: The value.
unit - String (optional, defaults to "ether"): The ether to convert from.

So you should provide the number as either a String or a BigNumber (Web3 0.2x) / BN (Web3 1.x).

Your code should then be:

let result = await instance.joinQuiz({
    from: accounts[1], 
    value: web3.utils.toWei("10", "wei")
});

However, in your code you're converting from wei to wei, which might not be what you want, so keep in mind that the second parameter is the unit you're converting from.