Improve exception handling

pyflowlauncher/event.py

@@ -1,5 +1,12 @@
 import asyncio
-from typing import Any, Callable, Iterable, Type
+from typing import Any, Callable, Iterable, Type, Union
+
+
+class EventNotFound(Exception):
+
+    def __init__(self, event: str):
+        self.event = event
+        super().__init__(f"Event '{event}' not found.")
 
 
 class EventHandler:
@@ -8,7 +15,7 @@ def __init__(self):
         self._events = {}
         self._handlers = {}
 
-    def _get_callable_name(self, method: Callable[..., Any]):
+    def _get_callable_name(self, method: Union[Callable[..., Any], Exception]):
         return getattr(method, '__name__', method.__class__.__name__).lower()
 
     def add_event(self, event: Callable[..., Any], *, name=None) -> str:
@@ -24,19 +31,26 @@ def add_exception_handler(self, exception: Type[Exception], handler: Callable[..
         self._handlers[exception] = handler
 
     def get_event(self, event: str) -> Callable[..., Any]:
-        return self._events[event]
+        try:
+            return self._events[event]
+        except KeyError:
+            raise EventNotFound(event)
 
     async def _await_maybe(self, result: Any) -> Any:
         if asyncio.iscoroutine(result):
             return await result
         return result
 
+    async def trigger_exception_handler(self, exception: Exception) -> Any:
+        try:
+            handler = self._handlers[exception.__class__]
+            return await self._await_maybe(handler(exception))
+        except KeyError:
+            raise exception
+
     async def trigger_event(self, event: str, *args, **kwargs) -> Any:
         try:
             result = self.get_event(event)(*args, **kwargs)
             return await self._await_maybe(result)
         except Exception as e:
-            handler = self._handlers.get(type(e), None)
-            if handler:
-                return handler(e)
-            raise e
+            return await self.trigger_exception_handler(e)