D003 int_beyond_js_safe_range
On the JS backend, an Int left the exactly representable range ±(2^53−1).
A runtime defect: the running program stops with it; no compile phase reports it, and try cannot catch it. sakura explain D003 prints this explanation offline.
On the JS backend, an Int left the exactly representable range ±(2^53−1). v0 traps instead of
computing a silently wrong value (design §4.1).
Runtime defects come from running programs, so compiler/tests/ui has no fixture for them; the explanation above names the repair.