Lower Hostcall error log level to DEBUG

[awilliams-fastly]

The Fastly CLI executes Viceroy with a -v argument, which corresponds to INFO log level. This change drops the log level of hostcall errors to DEBUG, so that they're not displayed to users running apps via fastly compute serve.

As an example, BufferLengthError is a sentinel error used to indicate to the caller that the passed in buffer was too small. The caller can then try again with an appropriately sized buffer.

[joeshaw]

My 2¢: I think it would be better to lower all the "hostcall yielded" error messages to DEBUG, as you'll see them for various other hostcalls when, for example, running the Go SDK's integration tests.

The fact that a hostcall returned an error to an SDK isn't indicative of a bug in the runtime, or the hostcall. In the case with BufferLengthError it's a negotiation between the runtime and the SDK of the appropriate buffer size, an implementation detail. But other times it may be caused by unimplemented behavior in Viceroy. Perhaps most commonly it's caused by user error, passing in bad data. Those errors should be passed through and reflected in errors by the SDK in the guest code.

[draco2003]

+1 for this fix.

Getting a similar error when code references the FetchEvent.client.tlsProtocol and run locally

[joeshaw]

👍