Table validation wrapped in assert — silently skipped under python -O / PYTHONOPTIMIZE=1

[timtreis]

Table validation wrapped in assert — silently skipped under python -O / PYTHONOPTIMIZE=1

Description

The call to _ensure_table_and_layer_exist_in_sdata(...) is wrapped in an assert statement (utils.py:~2554). Python's -O flag strips assert statements at compile time, so the entire validation function is never called in optimized mode. Passing a nonexistent table_name under python -O does not raise a clean ValueError; instead, the process crashes later with a cryptic AttributeError or KeyError deep in the rendering path. Docker-based deployments and some CI environments commonly use PYTHONOPTIMIZE=1.

User-input validation must never use assert. assert is documented by Python as an internal developer invariant check, explicitly removed under -O.

Environment

spatialdata-plot: 0.3.4.dev (main, 5cfedc7)
spatialdata: 0.5.0
Python: 3.13

Affected Code

# utils.py — current code (~line 2554)
assert _ensure_table_and_layer_exist_in_sdata(param_dict.get("sdata"), table_name, table_layer)
# Under python -O: this line is compiled away entirely — validation is silently bypassed

Running the render pipeline under python -O with table_name="nonexistent_table" does not raise ValueError: Table 'nonexistent_table' not found. The assert is stripped, validation is skipped, and the error surfaces later as an unrelated internal error with no useful message.

Expected vs. Actual

Expected: Passing an invalid table_name always raises a clear ValueError, regardless of interpreter optimization level.

Actual: Under python -O / PYTHONOPTIMIZE=1, the validation is silently skipped and the failure manifests as a cryptic internal error.

Fix Sketch

Replace the assert with an unconditional call. The function already raises ValueError internally when validation fails, so no additional error handling is needed:

# Instead of:
assert _ensure_table_and_layer_exist_in_sdata(sdata, table_name, table_layer)

# Use:
_ensure_table_and_layer_exist_in_sdata(sdata, table_name, table_layer)

Also audit the codebase for any other assert statements guarding user-input validation — this pattern may appear elsewhere.

Labels: bug, priority: medium

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Triage tier: Tier 2