[atharvmantri]

Summary

Guard the optimal-parser dictionary-statistics fast path on all four entropy repeat modes, not only the Huffman table mode.

Why

FSE_getMaxNbBits() intentionally returns a fake tableLog + 1 cost for zero-frequency symbols. A custom dictionary with incomplete FSE coverage can therefore reach the strict assert(bitCost < scaleLog) checks in ZSTD_rescaleFreqs() through the public ZSTD_createCDict_advanced() / ZSTD_compress_usingCDict() APIs, as described in #4681.

When any FSE table is incomplete, the existing no-dictionary-statistics initialization is the safe path. This avoids consuming incomplete dictionary tables without changing the valid-table path.

Validation

• git diff --check passes.
• Source review confirms the fallback initializes the literal, literal-length, match-length, and offset-code statistics.
• A native zstd build/reproducer was not available on this Windows host because no C compiler is installed.

Fixes #4681.

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