Sema: fix use of Zcu.LazySrcLoc in error message

It currently prints as:

:3:18: error: untagged union 'Zcu.LazySrcLoc{ .base_node_inst = InternPool.TrackedInst.Index(104), .offset = Zcu.LazySrcLoc.Offset{ .node_offset = Zcu.LazySrcLoc.Offset.TracedOffset{ .x = -2, .trace = (value tracing disabled) } } }' cannot be converted to integer
a221b2fbf2wooster0 committed on 12/8/2024, 5:23:57 PM· committed by Matthew Luggparente62aac3
2 files changedLine totals unavailable