explicit loop

Author: willmcgugan

src/textual_dev/server.py

@@ -46,11 +46,17 @@ def _run_devtools(
     def noop_print(_: str) -> None:
         pass
 
+    try:
+        loop = asyncio.get_event_loop()
+    except RuntimeError:
+        loop = asyncio.new_event_loop()
+
     try:
         run_app(
             app,
             port=DEVTOOLS_PORT if port is None else port,
             print=noop_print,
+            loop=loop,
         )
     except OSError:
         from rich import print