fix: explicit returns mixed with implicit (fall through) returns

[ethanyzhang]

In general, to fix mixed implicit/explicit returns, ensure every control path returns a value of the same type (or explicitly re-raises/propagates the error instead of returning). Here, execute_mysql_query explicitly returns the fetched rows on success but implicitly returns None on error. Without changing the external behavior too much, the cleanest approach is to make the except block explicitly return a safe, consistent value—an empty list—after logging the error. This preserves the current “log and swallow” error-handling style while avoiding the confusing None return.

Concretely, in benchmarks/scripts/mysql_utils.py, within execute_mysql_query, add a return [] statement inside the except Error as e: block, after the print(f"The error '{e}' occurred") line. No imports or additional helper methods are required. All changes are confined to the shown function; the rest of the file and other imports remain untouched.

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