Normalizer returns n. variant when given an out-of-bounds c. variant

[reece]

The normalizer is expected to always return a variant (or raise exception).

With out-of-bounds support (#437), the normalizer was intended to emit a log message and return the original variant unchanged if the variant was out of bounds. This works correctly with n. variants (and tests demonstrate this). However, c. variants are projected to n. for normalization. Then, when the n. was determined to be out-of-bounds, it is returned. The effect is c. in, n. out.