fix: remove duplicate array entry (#100)

Author: janpio

index.js

@@ -29,7 +29,6 @@ module.exports = (params) => {
     'ER_CON_COUNT_ERROR',
     'ER_USER_LIMIT_REACHED',
     'ER_OUT_OF_RESOURCES',
-    'ER_CON_COUNT_ERROR',
     'PROTOCOL_CONNECTION_LOST', // if the connection is lost
     'PROTOCOL_SEQUENCE_TIMEOUT', // if the connection times out
     'ETIMEDOUT' // if the connection times out