LibJS: Make Completion.[[Value]] non-optional

Instead, just use js_undefined() whenever the [[Value]] field is unused.
This avoids a whole bunch of presence checks.

Libraries/LibWeb/HTML/Navigable.cpp

@@ -1850,8 +1850,8 @@ GC::Ptr<DOM::Document> Navigable::evaluate_javascript_url(URL::URL const& url, U
     String result;
 
     // 9. If evaluationStatus is a normal completion, and evaluationStatus.[[Value]] is a String, then set result to evaluationStatus.[[Value]].
-    if (evaluation_status.type() == JS::Completion::Type::Normal && evaluation_status.value().has_value() && evaluation_status.value()->is_string()) {
-        result = evaluation_status.value()->as_string().utf8_string();
+    if (evaluation_status.type() == JS::Completion::Type::Normal && evaluation_status.value().is_string()) {
+        result = evaluation_status.value().as_string().utf8_string();
     } else {
         // 10. Otherwise, return null.
         return nullptr;

Libraries/LibWeb/HTML/Navigation.cpp

@@ -1143,7 +1143,7 @@ bool Navigation::inner_navigate_event_firing_algorithm(
             // 1. Append the result of invoking handler with an empty arguments list to promisesList.
             auto result = WebIDL::invoke_callback(handler, {});
             // This *should* be equivalent to converting a promise to a promise capability
-            promises_list.append(WebIDL::create_resolved_promise(realm, result.value().value()));
+            promises_list.append(WebIDL::create_resolved_promise(realm, result.value()));
         }
 
         // 3. If promisesList's size is 0, then set promisesList to « a promise resolved with undefined ».

Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp

@@ -82,7 +82,7 @@ JS::Completion ClassicScript::run(RethrowErrors rethrow_errors, GC::Ptr<JS::Envi
 
     // 2. Check if we can run script with realm. If this returns "do not run" then return NormalCompletion(empty).
     if (can_run_script(realm) == RunScriptDecision::DoNotRun)
-        return JS::normal_completion({});
+        return JS::normal_completion(JS::js_undefined());
 
     // 3. Prepare to run script given realm.
     prepare_to_run_script(realm);
@@ -112,7 +112,7 @@ JS::Completion ClassicScript::run(RethrowErrors rethrow_errors, GC::Ptr<JS::Envi
             clean_up_after_running_script(realm);
 
             // 2. Rethrow evaluationStatus.[[Value]].
-            return JS::throw_completion(*evaluation_status.value());
+            return JS::throw_completion(evaluation_status.value());
         }
 
         // 2. If rethrow errors is true and script's muted errors is true, then:
@@ -129,7 +129,7 @@ JS::Completion ClassicScript::run(RethrowErrors rethrow_errors, GC::Ptr<JS::Envi
 
         // 1. Report an exception given by evaluationStatus.[[Value]] for realms's global object.
         auto& window_or_worker = as<WindowOrWorkerGlobalScopeMixin>(realm.global_object());
-        window_or_worker.report_an_exception(*evaluation_status.value());
+        window_or_worker.report_an_exception(evaluation_status.value());
 
         // 2. Clean up after running script with realm.
         clean_up_after_running_script(realm);

Libraries/LibWeb/HTML/Scripting/ExceptionReporter.cpp

@@ -56,8 +56,7 @@ void report_exception_to_console(JS::Value value, JS::Realm& realm, ErrorInPromi
 void report_exception(JS::Completion const& throw_completion, JS::Realm& realm)
 {
     VERIFY(throw_completion.type() == JS::Completion::Type::Throw);
-    VERIFY(throw_completion.value().has_value());
-    report_exception_to_console(*throw_completion.value(), realm, ErrorInPromise::No);
+    report_exception_to_console(throw_completion.value(), realm, ErrorInPromise::No);
 }
 
 }

Libraries/LibWeb/HTML/Scripting/Fetching.cpp

@@ -843,7 +843,7 @@ void fetch_descendants_of_and_link_a_module_script(JS::Realm& realm,
 
         // If this throws an exception, set result's error to rethrow to that exception.
         if (linking_result.is_throw_completion())
-            module_script.set_error_to_rethrow(linking_result.release_error().value().value());
+            module_script.set_error_to_rethrow(linking_result.release_error().value());
 
         // 2. Run onComplete given moduleScript.
         on_complete->function()(module_script);

Libraries/LibWeb/HTML/Scripting/ImportMapParseResult.cpp

@@ -57,8 +57,7 @@ void ImportMapParseResult::visit_edges(Visitor& visitor)
                 visitor.visit(exception);
             },
             [&](JS::Completion const& completion) {
-                if (completion.value().has_value())
-                    visitor.visit(completion.value().value());
+                visitor.visit(completion.value());
             });
     }
 }