[GGRei]

Fix #27054

This patch fixes or-block fallback validation when an Option/Result expression is used inside an outer cast. The checker now validates the or-block default against the original unwrapped payload type, instead of letting the outer cast type leak into the fallback check. This covers both call expressions like int(result_f64() or { 3.0 }) and selector expressions like int(holder.x or { 3.0 }), with tests for literals, aliases, generics, parent return, none, error(...), and invalid fallback types.

Explicitly out of scope: h.x or {} and h.x or { side_effect }, because those are rejected earlier by selector_expr. Supporting that form would be a separate language/checker decision about whether selector or {} blocks without a value should be allowed, and that is not something I should decide in this patch. Also, struct fields cannot currently store Result types (!T), so there is no r !f64 selector-field test.