BUG: merge with mismatched index dtypes failing to raise
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Thanks @jbrockmendel  just a question: I believe this change alters edge case behavior of running pd.merge_asof(df, pd.DataFrame(), left_index=True, right_index=True) for a df with a datetime index.

pandas version 2.0.3 returns df for the above function call (instead of raising).

wondering whether this edge behavior ought to be preserved or if there is a better work around to potentially merging a non-empty with and empty df.