LibJS: Convert set_mutable_binding() to ThrowCompletionOr

Also add spec step comments to it while we're here.

1 files changed, 4 insertions, 3 deletions

diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index 18fbcd45b6..6fd525ecd1 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -166,9 +166,10 @@ Value FunctionDeclaration::execute(Interpreter& interpreter, GlobalObject& globa
 
     if (m_is_hoisted) {
         // Perform special annexB steps see step 3 of: https://tc39.es/ecma262/#sec-web-compat-functiondeclarationinstantiation
-        auto function_object = interpreter.vm().running_execution_context().lexical_environment->get_binding_value(global_object, name(), false);
-        interpreter.vm().running_execution_context().variable_environment->set_mutable_binding(global_object, name(), function_object, false);
-        VERIFY(!interpreter.exception());
+        auto* variable_environment = interpreter.vm().running_execution_context().variable_environment;
+        auto* lexical_environment = interpreter.vm().running_execution_context().lexical_environment;
+        auto function_object = lexical_environment->get_binding_value(global_object, name(), false);
+        MUST(variable_environment->set_mutable_binding(global_object, name(), function_object, false));
     }
 
     return {};