bug fixes

compiler/hir/hir.odin

@@ -132,6 +132,10 @@ Expr_Kind :: enum u8 {
 	Call,
 }
 
+CATCH_EXPRESSION         :: i64(0)
+CATCH_BLOCK              :: i64(1)
+CATCH_VOID_FALLTHROUGH   :: i64(2)
+
 Expr :: struct {
 	span:       source.Span,
 	type:       types.Type,
@@ -140,9 +144,9 @@ Expr :: struct {
 	// encoded as Expr_Id because it otherwise has no args.
 	args:       []Expr_Id,
 	// `Catch` block handlers use `body` for the handler statements and `target`
-	// for the optional captured error local. A missing `right` means the handler
-	// exits on every path and therefore has no fallback value. `Try` uses `body`
-	// for active error-exit cleanup.
+	// for the optional captured error local. `integer` selects the catch mode;
+	// a missing `right` means the block exits or completes with void. `Try` uses
+	// `body` for active error-exit cleanup.
 	body:       []Stmt_Id,
 	target:     Ref,
 	left:       Expr_Id,