Change some ERROR messages to WARNING messages, exists() to existsSync()
Change some ERROR messages to WARNING messages, exists() to existsSync()

xingwu1/azure-sdk-for-node,xingwu1/azure-sdk-for-node,Azure/azure-sdk-for-node,xingwu1/azure-sdk-for-node,Azure/azure-sdk-for-node,Azure/azure-sdk-for-node