conn: remove the log.Errorf for non-NFS protocol errors

The current code is calling log.Errorf for file system errors.
File system errors can be frequent, as in a shell searching $PATH.

These errors will be visible to the NFS client, and the NFS server
are very confusing when running shells on NFS-mounted file
systems, since the shell will handle the error.

The shell is just one example; searches of LD_LIBRARY_PATH,
/usr/include, etc: all produce copiuos error messages that
are not needed. The error is returned to the client and
can be handled there.

Note that if there is a protocol-level error, such as failure
to return a response packet, the error prints will still happen.
In that case, it may be appropriate.

Fixes #117.

Signed-off-by: Ronald G Minnich <[email protected]>

conn.go

@@ -127,7 +127,6 @@ func (c *conn) handle(ctx context.Context, w *response) error {
  return drainErr
  }
  if appError != nil && !w.responded {
- Log.Errorf("call to %+v failed: %v", handler, appError)
  if err := c.err(ctx, w, appError); err != nil {
  return err
  }