bashrc.cust: Add 'cust-error' function

This is a general error that will be used in other functions.

bashrc.cust

@@ -26,4 +26,11 @@ alias r='rm -fr'
 alias repoinit='repo init --no-clone-bundle'
 alias reposync='repo sync --force-sync --no-clone-bundle -c --no-tags'
 alias sudo='sudo '
-alias wget='wget --hsts-file /dev/null'
+alias wget='wget --hsts-file /dev/null'
+
+
+# Functions
+function cust-error {
+	echo "ERROR: Invalid argument(s)!"
+	exit 1
+}