Error Handling in MERN MATERIAL DEMO APP

dbErrorHandler.js

const getErrorMessage = err => {
	let message = '';
	if (err.code) {
		switch (err.code) {
			case 11000:
			case 11001:
				message = getUniqueErrorMessage(err);
				break;
			default:
				message = 'Something went wrong.';
		}
	} else {
		for (let errName in err.errors) {
			if (err.errors[errName].message) message = err.errors[errName].message;
		}
	}
	return message;
};

const getUniqueErrorMessage = err => {
	let output;
	try {
		let fieldName = err.message.substring(
			err.message.lastIndexOf('.$') + 2,
			err.message.lastIndexOf('_1')
		);
		output =
			fieldName.charAt(0).toUpperCase() +
			fieldName.slice(1) +
			' already exists';
	} catch (ex) {
		output = 'Field Already Exists!';
	}
	return output;
};

export default { getErrorMessage };