Returned error: VM Exception while processing transaction: revert when multiplying

Smart Contracts
1

I geting VM exception calling this function. Someone could give me a hint?

solidity ^0.8.7;

function ownerCheckReward(address _address) view external returns(uint){
    uint _moment = moment[_address];
    uint _allowance = allowance[_address];
    uint _timestamp = block.timestamp;
    uint mul = _moment * _allowance;
    uint result = _timestamp - mul;
    return result;
}

Var declaration:

mapping(address => uint) allowance;
mapping(address => uint) moment;

Test script

const PayRole = artifacts.require("Payrole")
const Token = artifacts.require("Token")

contract("PayRole", (accounts) => {
    it("Should allow the owner to add a new dev.", async () => {
        const _payrole = await PayRole.deployed();
        await _payrole.addDev.sendTransaction(accounts[2], 10000);
        const result = await _payrole.getStatus.call(accounts[2])
        assert.equal(result, true, "The dev address wasn't allowed")
    })
    it("Should allow anyone to send the specific token to the contract.", async () => {
        const _token = await Token.deployed()
        await _token.transfer('0x893BFba8e5d9Cbd998b248a39a4905E7DBD100FC', 10000, {from: accounts[0]})
        const balance = await _token.balanceOf.call('0x893BFba8e5d9Cbd998b248a39a4905E7DBD100FC')
        assert(balance.toNumber() >= 10000, 'Tokens not sent.')
    })
    it("Should allow owner to change allowance", async () => {
        const _payrole = await PayRole.deployed()
        const allowance = await _payrole.setAllowance.sendTransaction(accounts[2], 100000);
        assert(allowance, "Allowance wasn't changed")
    })
    it("Should return the numbers of tokens to be allowed every millisecond", async () => {
        const _payrole = await PayRole.deployed()
        const account = accounts[2]
        const result = await _payrole.ownerCheckReward.call(account)
        assert(result, "The function remain bugged")
    })
})

Test result

Test result

  Contract: PayRole
    √ Should allow the owner to add a new dev. (813ms)
    √ Should allow anyone to send the specific token to the contract. (824ms)
    √ Should allow owner to change allowance (712ms)
    1) Should return the numbers of tokens to be allowed every millisecond
    > No events were emitted


  3 passing (4s)
  1 failing

  1) Contract: PayRole
       Should return the numbers of tokens to be allowed every millisecond:
     Error: Returned error: VM Exception while processing transaction: revert
      at Context.<anonymous> (test\payroles.js:25:56)
      at processTicksAndRejections (node:internal/process/task_queues:96:5)
2

Hey @burgossrodrigo can you tell which is the value of "mul" ?