Fix access violation if callbacks are added or removed while a callback is being processed

Author: tt2468

setup.py

@@ -10,7 +10,7 @@
 
 setuptools.setup(
     name="simpleobsws",
-    version="1.4.2",
+    version="1.4.3",
     author="tt2468",
     author_email="tt2468@gmail.com",
     description="A simple obs-websocket library in async Python for people who just want JSON output.",

simpleobsws.py

@@ -242,12 +242,16 @@ def register_event_callback(self, callback, event: str = None):
         if not inspect.iscoroutinefunction(callback):
             raise EventRegistrationError('Registered functions must be async')
         else:
-            self.event_callbacks.append((callback, event))
+            event_callbacks_copy = self.event_callbacks.copy()
+            event_callbacks_copy.append((callback, event))
+            self.event_callbacks = event_callbacks_copy
 
     def deregister_event_callback(self, callback, event: str = None):
-        for c, t in self.event_callbacks.copy():
+        event_callbacks_copy = self.event_callbacks.copy()
+        for c, t in self.event_callbacks: # We can use the old event_callbacks list to avoid our iterator being invalidated
             if (c == callback) and (event == None or t == event):
-                self.event_callbacks.remove((c, t))
+                event_callbacks_copy.remove((c, t))
+        self.event_callbacks = event_callbacks_copy
 
     def is_identified(self):
         return self.identified