GUI popup for uncaught asyncio loop exceptions

TODO.md

@@ -3,9 +3,6 @@
 - Make dark bar extend down pane
 - Verify default size
 
-- catch py unretrieved exception
-- call default handler from signin & others
-
 ## Media
 
 - nio ClientTimeout
@@ -55,7 +52,6 @@
 - `EventImage`s for `m.image` sometimes appear broken, can be made normal
   by switching to another room and coming back
 - First sent message in E2E room is sometimes undecryptable
-- Handle matrix errors for accept/decline invite buttons and other
 
 - Pause upload, switch to other room, then come back → wrong state displayed
 - Pausing uploads doesn't work well, servers end up dropping the connection 

src/backend/pyotherside_events.py

@@ -49,6 +49,15 @@ class CoroutineDone(PyOtherSideEvent):
     traceback: Optional[str]       = None
 
 
+@dataclass
+class LoopException(PyOtherSideEvent):
+    """Indicate that an uncaught exception occured in the asyncio loop."""
+
+    message:   str                 = field()
+    exception: Optional[Exception] = field()
+    traceback: Optional[str]       = None
+
+
 @dataclass
 class ModelUpdated(PyOtherSideEvent):
     """Indicate that a backend `Model`'s data changed."""

src/backend/qml_bridge.py

@@ -12,7 +12,7 @@ from threading import Thread
 from typing import Coroutine, Sequence
 
 from .backend import Backend
-from .pyotherside_events import CoroutineDone
+from .pyotherside_events import CoroutineDone, LoopException
 
 try:
     import uvloop
@@ -39,9 +39,24 @@ class QMLBridge:
         self.backend: Backend = Backend()
 
         self._loop = asyncio.get_event_loop()
+        self._loop.set_exception_handler(self._loop_exception_handler)
+
         Thread(target=self._start_asyncio_loop).start()
 
 
+    def _loop_exception_handler(
+        self, loop: asyncio.AbstractEventLoop, context: dict,
+    ) -> None:
+        if "exception" in context:
+            err   = context["exception"]
+            trace = "".join(
+                traceback.format_exception(type(err), err, err.__traceback__),
+            )
+            LoopException(context["message"], err, trace)
+
+        loop.default_exception_handler(context)
+
+
     def _start_asyncio_loop(self) -> None:
         asyncio.set_event_loop(self._loop)
         self._loop.run_forever()

src/gui/Popups/UnexpectedErrorPopup.qml

@@ -16,12 +16,12 @@ BoxPopup {
 
 
     property string errorType
-    property var errorArguments: []
+    property string message: ""
     property string traceback: ""
 
 
     HScrollableTextArea {
-        text: traceback || qsTr("No traceback available")
+        text: [message, traceback].join("\n\n") || qsTr("No info available")
         area.readOnly: true
 
         Layout.fillWidth: true

src/gui/PythonBridge/EventHandlers.qml

@@ -47,7 +47,7 @@ QtObject {
             utils.makePopup(
                 "Popups/UnexpectedErrorPopup.qml",
                 window,
-                { errorType: type, errorArguments: args, traceback },
+                { errorType: type, traceback },
             )
         }
 
@@ -55,6 +55,25 @@ QtObject {
     }
 
 
+    function onLoopException(message, error, traceback) {
+        // No need to log these here, the asyncio exception handler does it
+        const type = py.getattr(py.getattr(error, "__class__"), "__name__")
+
+        if (window.hideErrorTypes.has(type)) {
+            console.warn(
+                "Not showing error popup for this type due to user choice"
+            )
+            return
+        }
+
+        utils.makePopup(
+            "Popups/UnexpectedErrorPopup.qml",
+            window,
+            { errorType: type, message, traceback },
+        )
+    }
+
+
     function onModelUpdated(syncId, data, serializedSyncId) {
         if (serializedSyncId === "Account" || serializedSyncId[0] === "Room") {
             py.callCoro("get_flat_mainpane_data", [], data => {