usb/sagas: Delay connection attempt on hotplug.

If we try to connect too soon, we get security errors.

Author: laurensvalk

lib/pybricks-blocks

@@ -0,0 +1 @@
+Subproject commit 544b33a507a3a3c368df7b8057b7c63d3ff6caa0

src/usb/sagas.ts

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2025 The Pybricks Authors
+// Copyright (c) 2025-2026 The Pybricks Authors
 
 import { firmwareVersion } from '@pybricks/firmware';
 import { AnyAction } from 'redux';
@@ -77,6 +77,11 @@ function* handleUsbConnectPybricks(hotPlugDevice?: USBDevice): Generator {
     // so that reducers still work correctly.
     if (hotPlugDevice !== undefined) {
         yield* put(usbHotPlugConnectPybricks());
+
+        // Even though we get the connect event, the browser does not
+        // appear to be ready to open the device right away, so we add a
+        // small delay before trying to connect.
+        yield* delay(100);
     }
 
     if (navigator.usb === undefined) {
@@ -655,6 +660,8 @@ function* handleUsbConnectEvent(): Generator {
         // if there is exactly one Pybricks device connected, we can connect to
         // it, otherwise we should let the user choose which one to connect to
         if (pybricksDevices.length === 1) {
+            // REVISIT: Device is passed as hotplug device, even though it is
+            // not technically a hotplug event.
             yield* spawn(handleUsbConnectPybricks, pybricksDevices[0]);
         }
     }