`estimated_compression_context_size()` raises SIGFPE with `enable_ldm=True

[marinelay]

Summary

Calling estimated_compression_context_size() on compression parameters constructed with enable_ldm=True terminates Python with SIGFPE.

Versions

zstandard 0.25.0, CPython 3.12.3, Ubuntu 24.04.4 x86_64, glibc 2.39.

Reproducer

import zstandard as zstd

params = zstd.ZstdCompressionParameters.from_level(3, enable_ldm=True)
params.estimated_compression_context_size()

This one exited with SIGFPE (signal 8; shell status 136).

I found this while fuzzing Python C extension modules.
I would expect a size estimate or a Python exception rather than process termination.