Logs with prefetch warnings

[an2n]

We’re seeing the following warning for every page during registerInitialCache:

[CacheHandler] [registerInitialCache] Failed to read page prefetch data, assuming it does not exist
Error: ENOENT: no such file or directory, open '/path/to/file.prefetch.rsc'

Since .prefetch.rsc files are optional, it might make sense to wrap this log statement in the existing debug condition to reduce noise in the logs.

I’m happy to open a PR for this change.

[AyronK]

@an2n sure! Just open a PR if you can, otherwise I'll take a look when I have time.

[AyronK]

Fixed in #118 and 2.1.3