Added an error message

Author: k1-801

windows/hid.c

@@ -386,6 +386,9 @@ int HID_API_EXPORT hid_init(void)
     register_global_error(NULL);
     if (!hid_hotplug_context.mutex) {
         hid_hotplug_context.mutex = CreateMutexA(NULL, FALSE, NULL);
+        if(!hid_hotplug_context.mutex) {
+            register_global_error(L"Failed to create hotplug management mutex");
+        }
     }
 #ifndef HIDAPI_USE_DDK
 	if (!hidapi_initialized) {
@@ -410,9 +413,11 @@ static void hid_internal_cleanup_hotplugs()
             hid_hotplug_context.devs = NULL;
         }
 
-        if (CM_Unregister_Notification(hid_hotplug_context.notify_handle) != CR_SUCCESS) {
-            register_global_error(L"hid_hotplug_deregister_callback/CM_Unregister_Notification");
-            return;
+        if (hid_hotplug_context.notify_handle) {
+            if (CM_Unregister_Notification(hid_hotplug_context.notify_handle) != CR_SUCCESS) {
+                register_global_error(L"hid_hotplug_deregister_callback/CM_Unregister_Notification");
+                return;
+            }
         }
 
         hid_hotplug_context.notify_handle = NULL;