Avoid printing the following log

```
API: SYSTEM
Time: Fri Jul 08 2022 11:48:40 GMT+0100
Error: Error(disk not found) reading erasure shards at...

Backtrace:
0: internal/logger/logger.go:278:logger.LogIf()
1: cmd/bitrot-streaming.go:156:cmd.(*streamingBitrotReader).ReadAt()
2: cmd/erasure-decode.go:165:cmd.(*parallelReader).Read.func1()
```