Avoid double handling of static file serving errors
Avoid double handling of static file serving errors

The static file manager would handle an `io_channel_read` error both in the read block and the cleanup handler. The error handler block would finish the response, thus leading to an unhandled exception (response already finished).

The following changes were made:

1. only handle the io error in the cleanup block.
2. do not invoke the error handler if data for the file has already been served as we just end up appending our error string to whatever was served of the file.

thecatalinstan/Criollo,thecatalinstan/Criollo,T1V/Criollo,T1V/Criollo,thecatalinstan/Criollo,T1V/Criollo,T1V/Criollo