How to handle VFS proxy error in WSO2 EI 6.4? - error-handling

Question

In VFS proxy, How I can handle errors? For example in below cases:
If VFS is not able to connect to SFTP server due to different reasons(like wrong password, directory not exist etc). I am able to see Warning in console log but I want to send a mail or want to do some other stuff if connection is not possible.
If the folder does not exist where we have to move file after reading.
I am able to handle error during processing in FaultSequence but that thing does not work for proxy. I tried to set onError attribute as well but seems proxy does not support that attribute.
Please let me know if someone handle such errors or I am missing something.
<proxy name="FileProxy" startOnLoad="false" statistics="enable" trace="enable" transports="vfs" xmlns="http://ws.apache.org/ns/synapse">
<target faultSequence="Global_Error_Handler">
<inSequence>
<log level="custom">
<property name="status=" value="File received."/>
</log>
</inSequence>
<outSequence/>
</target>
<parameter name="transport.vfs.Streaming">true</parameter>
<parameter name="transport.PollInterval">10</parameter>
<parameter name="transport.vfs.FileURI">vfs:sftp://abc:***#127.0.0.1:22/test/ftp_in?transport.vfs.AvoidPermissionCheck=true</parameter>
<parameter name="transport.vfs.ContentType">text/plain</parameter>
<parameter name="transport.vfs.ActionAfterProcess">MOVE</parameter>
<parameter name="transport.vfs.MoveAfterFailure">vfs:sftp://abc:***#127.0.0.1:22/test/ftp_failure</parameter>
<parameter name="transport.vfs.ActionAfterFailure">MOVE</parameter>
<parameter name="transport.vfs.ReplyFileName">ReplyFileName.csv</parameter>
<parameter name="transport.vfs.FileNamePattern">.*.dat</parameter>
<parameter name="transport.vfs.MoveAfterProcess">file:///home/test/ftp_process</parameter>
</proxy>
Need to handle any error that occurs outside the <target> functionality of proxy for VFS.