Add errors for invalid parameter

lib/errors.js

@@ -6,6 +6,13 @@ let Errors = {
 	invalidLoginCredentials: 'Invalid login credentials were provided',
 	requestNotAuthorized: 'The request was not authorized',
 	invalidToken: 'The token provided was not valid',
+	invalidParameter (param, message) {
+		if(message) {
+			var punctuatedMessage = ': ' + message
+		}
+
+		return `Parameter "${param}" is invalid${punctuatedMessage}`
+	}
 	missingParameter (param) {
 		return `The request is missing the parameter "${param}"`
 	},