Kernel: Add some asserts to enforce the invariants in the scheduler.

src/core/hle/kernel/kernel.cpp

@@ -27,6 +27,9 @@ void WaitObject::AddWaitingThread(SharedPtr<Thread> thread) {
 
 void WaitObject::RemoveWaitingThread(Thread* thread) {
     auto itr = std::find(waiting_threads.begin(), waiting_threads.end(), thread);
+    // If a thread passed multiple handles to the same object,
+    // the kernel might attempt to remove the thread from the object's
+    // waiting threads list multiple times.
     if (itr != waiting_threads.end())
         waiting_threads.erase(itr);
 }
@@ -36,6 +39,11 @@ SharedPtr<Thread> WaitObject::GetHighestPriorityReadyThread() {
     s32 candidate_priority = THREADPRIO_LOWEST + 1;
 
     for (const auto& thread : waiting_threads) {
+        // The list of waiting threads must not contain threads that are not waiting to be awakened.
+        ASSERT_MSG(thread->status == THREADSTATUS_WAIT_SYNCH_ANY ||
+                       thread->status == THREADSTATUS_WAIT_SYNCH_ALL,
+                   "Inconsistent thread statuses in waiting_threads");
+
         if (thread->current_priority >= candidate_priority)
             continue;
 

src/core/hle/kernel/thread.cpp

@@ -200,7 +200,7 @@ static void SwitchContext(Thread* new_thread) {
 
     // Load context of new thread
     if (new_thread) {
-        DEBUG_ASSERT_MSG(new_thread->status == THREADSTATUS_READY,
+        ASSERT_MSG(new_thread->status == THREADSTATUS_READY,
                    "Thread must be ready to become running.");
 
         // Cancel any outstanding wakeup events for this thread
@@ -307,6 +307,8 @@ void Thread::WakeAfterDelay(s64 nanoseconds) {
 }
 
 void Thread::ResumeFromWait() {
+    ASSERT_MSG(wait_objects.empty(), "Thread is waking up while waiting for objects");
+
     switch (status) {
     case THREADSTATUS_WAIT_SYNCH_ALL:
     case THREADSTATUS_WAIT_SYNCH_ANY:
@@ -580,6 +582,7 @@ void Thread::SetWaitSynchronizationOutput(s32 output) {
 }
 
 s32 Thread::GetWaitObjectIndex(WaitObject* object) const {
+    ASSERT_MSG(!wait_objects.empty(), "Thread is not waiting for anything");
     auto match = std::find(wait_objects.rbegin(), wait_objects.rend(), object);
     return std::distance(match, wait_objects.rend()) - 1;
 }