The message data property of an Error instance is a human-readable description of the error.
Value
A string corresponding to the value passed to the Error() constructor as the first argument.
Description
This property contains a brief description of the error if one is available or has been set. The message property combined with the name property is used by the Error.prototype.toString method to create a string representation of the Error.
By default, the message property is an empty string, but this behavior can be overridden for an instance by specifying a message as the first argument to the Error constructor.
Examples
Throwing a custom error
const e = new Error("Could not parse input");
// e.message is 'Could not parse input'
throw e;