--- a/dom/promise/Promise.cpp
+++ b/dom/promise/Promise.cpp
@@ -565,16 +565,19 @@ Promise::PerformMicroTaskCheckpoint()
 }
 
 void
 Promise::PerformWorkerMicroTaskCheckpoint()
 {
   MOZ_ASSERT(!NS_IsMainThread(), "Wrong thread!");
 
   CycleCollectedJSContext* context = CycleCollectedJSContext::Get();
+  if (!context) {
+    return;
+  }
 
   for (;;) {
     // For a normal microtask checkpoint, we try to use the debugger microtask
     // queue first. If the debugger queue is empty, we use the normal microtask
     // queue instead.
     std::queue<nsCOMPtr<nsIRunnable>>* microtaskQueue =
       &context->GetDebuggerPromiseMicroTaskQueue();
 
@@ -599,16 +602,19 @@ Promise::PerformWorkerMicroTaskCheckpoin
 }
 
 void
 Promise::PerformWorkerDebuggerMicroTaskCheckpoint()
 {
   MOZ_ASSERT(!NS_IsMainThread(), "Wrong thread!");
 
   CycleCollectedJSContext* context = CycleCollectedJSContext::Get();
+  if (!context) {
+    return;
+  }
 
   for (;;) {
     // For a debugger microtask checkpoint, we always use the debugger microtask
     // queue.
     std::queue<nsCOMPtr<nsIRunnable>>* microtaskQueue =
       &context->GetDebuggerPromiseMicroTaskQueue();
 
     if (microtaskQueue->empty()) {