fix for #209

lightrag/lightrag.py

@@ -52,15 +52,28 @@
 
 
 def always_get_an_event_loop() -> asyncio.AbstractEventLoop:
+    """
+    Ensure that there is always an event loop available.
+
+    This function tries to get the current event loop. If the current event loop is closed or does not exist,
+    it creates a new event loop and sets it as the current event loop.
+
+    Returns:
+        asyncio.AbstractEventLoop: The current or newly created event loop.
+    """
     try:
-        return asyncio.get_event_loop()
+        # Try to get the current event loop
+        current_loop = asyncio.get_event_loop()
+        if current_loop._closed:
+            raise RuntimeError("Event loop is closed.")
+        return current_loop
 
     except RuntimeError:
+        # If no event loop exists or it is closed, create a new one
         logger.info("Creating a new event loop in main thread.")
-        loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(loop)
-
-        return loop
+        new_loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(new_loop)
+        return new_loop
 
 
 @dataclass