message: Replace the empty Anchor check with the error log.
diff: @@ -1245,8 +1245,9 @@ void KytheFactsExtractor::CreateAnchorReferences(
  VName KytheFactsExtractor::CreateAnchor(const Anchor& anchor) {
  const int start_location = anchor.StartLocation();
  const int end_location = start_location + anchor.ContentLength();
  - CHECK(start_location != end_location)
  - << "Zero-sized Anchor! File: " << FilePath();
  + if (start_location == end_location) {
  + LOG(ERROR) << "Zero-sized Anchor! File: " << FilePath();
  + }
  const auto [location_str, _] = signature_locations_.emplace(
  absl::StrCat("@", start_location, ":", end_location));
  VName anchor_vname = {.path = FilePath(),
  