If reading encounters an unexpected end of data, inject a failure into the `Reader` instead of checking `healthy()`.
If reading encounters an unexpected end of data, inject a failure
into the `Reader` instead of checking `healthy()`.

This lets the `Reader` amend the status with more details.

PiperOrigin-RevId: 311294593

google/riegeli,google/riegeli,google/riegeli,google/riegeli