report error to client when read request fails

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### Describe the problem you're observing
The client hangs after writing data, then trying to read it in the same program. It works if you close the file in between, but it should at least error out if the data has not been synced yet.

### Describe how to reproduce the problem
Run a client application that writes data to a UnifyCR intercepted path, then try to read that data back without closing the file handle before the read. When you do this the client just hangs. This should report an error if the read lookup fails.

Reproduce the issue with a client writing to a UnifyCR intercepted path and reading before closing the file handle. Trace the read request and its lookup failure, then verify that the client reports an error instead of hanging when the data has not been synced.

Written by the indexing model from the issue text.