[#607] *: Remove redundant if on error returns

Semantic patch:
```
@@
@@
-if err != nil { return err }
-return nil
+return err
```

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/local_object_storage/blobstor/compression/compress.go

@@ -33,11 +33,7 @@ func (c *Config) Init() error {
 	}
 
 	c.decoder, err = zstd.NewReader(nil)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return err
 }
 
 // NeedsCompression returns true if the object should be compressed.