What command is used to handle errors in JavaScript promises?

The command used to handle errors in JavaScript promises is catch(). This method is specifically designed to handle any errors that occur during the execution of a promise. When a promise is rejected, the catch() method allows you to specify a function that will run to manage that error, providing an opportunity to implement error handling logic, such as logging the error or displaying an error message to the user.

The catch() method is a part of the promise chain and can be called after a then() block to capture any rejections from the previous promise in the chain. This is particularly useful for ensuring that your code can gracefully manage unexpected situations, maintaining a robust application.

The other choices do not exist as standard methods for error handling in promises. Therefore, catch() is the only correct and relevant option to handle errors within the context of JavaScript promises.