Make the errors we return when parsing an ECHConfig slightly more
verbose.
Fixes #71706
Change-Id: Id138fd9defec71ce492a490a71af4981cb9ede51
Reviewed-on: https://go-review.googlesource.com/c/go/+/650720
Auto-Submit: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Daniel McCarney <daniel@binaryparadox.net> Reviewed-by: Michael Knyszek <mknyszek@google.com>