Lots of logs about attempts to mutate an empty object

[kranonetka]

Describe the bug
When running fuzzing, many log entries appear like this:

[2024-11-06T08:04:52Z INFO  wuppiefuzz::openapi_mutator] Tried to mutate empty object; skipping. If this happens a lot WuppieFuzz may need improvement on this.

Versions:

• OS: any
• rustc: any
• Wuppiefuzz: v1.1.0

To Reproduce
OpenAPI spec: openapi.yaml
cmd:

./wuppiefuzz fuzz \
  -i corpus_directory \
  --coverage-host localhost:6300 \
  --coverage-format jacoco \
  --timeout 600 \
  --jacoco-class-dir ~service/target/classes \
  --source-dir ~/service/src/main/java \
  --output-format human-readable \
  --header header.yaml \
  --log-level info \
  --method-mutation-strategy follow-spec \
  --jacoco-class-prefix org/keycloak/services/resources \
  --report \
  --crash-criterion only5xx \
  openapi.yaml

Expected behavior
WuppieFuzz should be improved to reduce the frequency of "Tried to mutate empty object" log entries.