Missing input validation could cause unexpected behavior with edge case inputs

[goransh-buh]

Bug Report

Description

Some functions do not validate their inputs before processing, which can lead to confusing error messages or silent failures when unexpected values are passed.

Steps to Reproduce

1. Call the affected function with None, an empty string, or a negative number
2. Observe that the error message is not helpful or the function silently returns incorrect results

Expected Behavior

Functions should validate inputs early and raise descriptive errors:

def process(value):
    if value is None:
        raise ValueError("value must not be None")
    if not isinstance(value, int):
        raise TypeError(f"expected int, got {type(value).__name__}")
    # ... rest of function

Impact

This makes debugging harder for users of the library and can hide real bugs upstream.

Suggested Fix

Add input validation at the start of public-facing functions with clear error messages.