added try for sql connect

seafile-ldap.py

@@ -145,8 +145,17 @@ dbconfig = {
   'raise_on_warnings': True
 }
 logger.debug("Starting SQL query for LDAPUsers")
-cnx = mysql.connector.connect(**dbconfig)
-logger.debug("SQL Connection: {0}".format(cnx))
+try:
+    cnx = mysql.connector.connect(**dbconfig)
+    logger.debug("SQL Connection: {0}".format(cnx))
+except mysql.connector.Error as err:
+    if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
+        logger.critical("Something is wrong with your user name or password")
+    elif err.errno == errorcode.ER_BAD_DB_ERROR:
+        logger.critical("Database does not exist")
+    else:
+        logger.critical(err)
+    exit(3)
 cursor = cnx.cursor()
 query = ("SELECT * FROM LDAPUsers")
 logger.debug("Query: {0}".format(query))