Add validateAccountID middleware to account routes

middlewares/validateAccountID.js

@@ -0,0 +1,23 @@
+const Account = require('../api/models/accountModel');
+
+async function validateAccountID(req, res, next) {
+	const { id } = req.params;
+
+	try {
+		const account = await Account.getAccountById(id);
+		if (typeof account == 'undefined') {
+			return res.status(404).json({
+				message: `Account with id ${id} doesn't exist.`,
+			});
+		} else {
+			next();
+		}
+	} catch (error) {
+		res.status(500).json({
+			message: `Failed to fetch account with id ${id}.`,
+			error,
+		});
+	}
+}
+
+exports.validateAccountID = validateAccountID;