gas estimation errored with the following message - execution reverted - cryptography

Question

// SPDX-License-Identifier: MIT
pragma solidity >=0.6.6 < 0.9.0;
import "#chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";
contract FundMe {
mapping(address => uint256) public addressToAmountFunded;
function fund() public payable {
uint256 minimumUSD = 30 * 10 ** 18;
require(getConversionRate(msg.value) >= minimumUSD, "You need to spend more ETH");
addressToAmountFunded[msg.sender] += msg.value;
}
function getVersion() public view returns (uint256) {
AggregatorV3Interface priceFeed = AggregatorV3Interface(0x8A753747A1Fa494EC906cE90E9f37563A8AF630e);
return priceFeed.version();
}
address public owner;
constructor() public {
owner = msg.sender;
}
function getPrice() public view returns (uint256) {
AggregatorV3Interface priceFeed = AggregatorV3Interface(0x8A753747A1Fa494EC906cE90E9f37563A8AF630e);
(,int256 answer,,,) = priceFeed.latestRoundData();
return uint256(answer * 10000000000);
}
function getConversionRate(uint256 ethAmount) public view returns (uint256) {
uint256 ethPrice = getPrice();
uint256 ethAmountInUsd = (ethPrice * ethAmount)/1000000000000000000;
return ethAmountInUsd;
}
function withdraw() public payable {
require(msg.sender == owner);
payable(msg.sender).transfer(address(this).balance);
}
}
I write this piece of code. I get this message every time I deploy:
"gas estimation errored with the following message - execution reverted"
I know problem is in:
function fund() public payable {
uint256 minimumUSD = 30 * 10 ** 18;
require(getConversionRate(msg.value) >= minimumUSD, "You need to spend more ETH");
addressToAmountFunded[msg.sender] += msg.value;
}
In this function I try to avoid geting value below 30$.
Can anybody help me?