void someFunction() { // Some condition to check for an error bool isErrorOccurred = true; if (isErrorOccurred) { // Throw an error with a custom message throw 'An error occurred!'; } // Other code if no error occurred // ... }class CustomException implements Exception { String cause; CustomException(this.cause); } void main() { try { throwException(); } on CustomException { print("custom exception has been obtained"); } } throwException() { throw new CustomException('This is my first custom exception'); }void validate_age(int age) { if(age < 0) { throw new FormatException(); } }void main() { try { someFunction(); } catch (e) { print('Caught an error: $e'); // Handle the error here, such as showing a user-friendly error message } }