Verify Kraft's inequality is not violated

[fkjellberg]

Generated-by: Claude Opus 5 noreply@anthropic.com

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The documentation for HuffmanDecoder states that the code lengths must not violate Kraft's inequality but this is never checked. It turns out that some of the existing test cases violate this prerequisite.

HuffmanDecoder will now throw CompressorException if the code lengths violate Kraft's inequality. Without this early check before actually start decoding, the decoder may output corrupt data that hopefully will be detected by the CRC checksum or it may throw other unexpected exceptions while decoding the input stream.

I used Claude Opus 5 to generate some of the code and to help investigate and fix the failing test cases.

Generated-by: Claude Opus 5 noreply@anthropic.com

[garydgregory]

Hello @fkjellberg

Thank you for the PR.

A few comments:

• There are no explicit test for a Kraft violation where minCodeLength > 1 or for a violation at a deeper length > 2. The current test only hits length 2.
• The class-level comment could mention “Kraft’s inequality”.
• The exception message could add the offending count and available nodes to aid debugging, but is not required.