panic: date_trunc unwraps out-of-range lower-bound timestamp truncation

[Dandandan]

Describe the bug

date_trunc can panic during planning/constant folding for lower-bound nanosecond timestamps. Truncating to a coarser unit can produce a value outside Arrow's nanosecond timestamp range, and the code unwraps None.

To Reproduce

EXPLAIN SELECT date_trunc('year', TIMESTAMP '1677-09-22 00:00:00');

Actual behavior

thread 'main' panicked at datafusion/functions/src/datetime/date_trunc.rs:649:14:
called `Option::unwrap()` on a `None` value

Expected behavior

Return an error or NULL for an out-of-range truncated timestamp; do not panic.

Notes

Other coarse granularities near the lower nanosecond timestamp bound hit the same unwrap.