Errors.md

91 - Errors

A Error(string) exception (or an exception without data) is generated in the following situations:

1. Calling require with an argument that evaluates to false.

2. If you perform an external function call targeting a contract that contains no code

3. If your contract receives Ether via a public function without payable modifier (including the Constructor and the Fallback function)

4. If your contract receives Ether via a public getter function

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Slide Screenshot

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Slide Deck

• Error(string)
• require(Arg == false)
• revert([String])
• Receive ETH -> No payable public Function/Getter

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References

• Youtube Reference
• Solidity by Example - Error

Solidity by Example

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

contract Error {
    function testRequire(uint _i) public pure {
        // Require should be used to validate conditions such as:
        // - inputs
        // - conditions before execution
        // - return values from calls to other functions
        require(_i > 10, "Input must be greater than 10");
    }

    function testRevert(uint _i) public pure {
        // Revert is useful when the condition to check is complex.
        // This code does the exact same thing as the example above
        if (_i <= 10) {
            revert("Input must be greater than 10");
        }
    }

    uint public num;

    function testAssert() public view {
        // Assert should only be used to test for internal errors,
        // and to check invariants.

        // Here we assert that num is always equal to 0
        // since it is impossible to update the value of num
        assert(num == 0);
    }

    // custom error
    error InsufficientBalance(uint balance, uint withdrawAmount);

    function testCustomError(uint _withdrawAmount) public view {
        uint bal = address(this).balance;
        if (bal < _withdrawAmount) {
            revert InsufficientBalance({balance: bal, withdrawAmount: _withdrawAmount});
        }
    }
}