huh apparently this works

src/compiler/compile/nodes/shared/Expression.ts

@@ -140,6 +140,7 @@ export default class Expression {
 					if (template_scope.is_let(name)) {
 						if (!function_expression) { // TODO should this be `!lazy` ?
 							contextual_dependencies.add(name);
+							dependencies.add(name);
 						}
 					} else if (template_scope.names.has(name)) {
 						expression.uses_context = true;