firmware/sagas: add delay after connecting

This adds a delay after connecting to a hub when flashing firmware via
BLE before sending any commands. This gives the OS Bluetooth stack time
to finish enumerating the Bluetooth device before we start trying to
interact with the device. Hopefully this fixes issues for some people
who are seeing problems while flashing firmware.

Issue: https://github.com/orgs/pybricks/discussions/792

CHANGELOG.md

@@ -6,8 +6,10 @@
 
 ### Fixed
 - Fixed app freezing when checking for updates and update server is unreachable ([pybricks-code#1299]).
+- Added delay to try to mitigate errors when flashing firmware on city hubs ([support#792]).
 
 [pybricks-code#1299]: https://github.com/pybricks/pybricks-code/issues/1299
+[support#792]: https://github.com/orgs/pybricks/discussions/792
 
 ## [2.0.0-beta.10] - 2022-11-11
 

src/firmware/sagas.ts

@@ -393,6 +393,12 @@ function* handleFlashFirmware(action: ReturnType<typeof flashFirmware>): Generat
             return;
         }
 
+        // istanbul ignore if
+        if (process.env.NODE_ENV !== 'test') {
+            // give OS Bluetooth stack some time to settle
+            yield* delay(1000);
+        }
+
         const nextMessageId = yield* getContext<() => number>('nextMessageId');
 
         const infoAction = yield* put(infoRequest(nextMessageId()));