Prevents:
error: variable 'letParameter' set but not used

--- a/src/wiz/compiler/compiler.cpp
+++ b/src/wiz/compiler/compiler.cpp
@@ -5311,6 +5311,7 @@ namespace wiz {
                         auto& argument = arguments[i];
 
                         if (auto letParameter = parameter->tryGet<Definition::Let>()) {
+                            (void)letParameter;
                             if (argument->info->context == EvaluationContext::RunTime) {
                                 report->error("argument `" + parameter->name.toString() + "` is a `let` expression, so it cannot accept a run-time expression", argument->location);
                             }