As the community progressively moves to a useful practice of enabling
ruby warnings on tests, assigning an instance variable before use becomes
a necessary practice. Here we set some variables at initialization that
were previously lazily or conditionally set:
- `decoded` is assigned false which seems to make more semantic sense
than than using nil
- `namespace` is assigned nil, its value being lazily computed later
- `available_namespaces` is assigned nil so as to respect the cache
invalidation mechanism