Fix: return failure when PhoneAPI times out (#3136)

* Add debug options for RP2040

* Rename: "observed" should be plural: "observables"

* PhoneAPI: return failure on timeout
In `onNotify()`, when disconnected, PhoneAPI removed itself from the list of observers that was looped through in `notifyObservers()`. We should exit that loop in that case.

src/mesh/PhoneAPI.cpp

@@ -62,15 +62,17 @@ void PhoneAPI::close()
     }
 }
 
-void PhoneAPI::checkConnectionTimeout()
+bool PhoneAPI::checkConnectionTimeout()
 {
     if (isConnected()) {
         bool newContact = checkIsConnected();
         if (!newContact) {
             LOG_INFO("Lost phone connection\n");
             close();
+            return true;
         }
     }
+    return false;
 }
 
 /**
@@ -461,8 +463,8 @@ bool PhoneAPI::handleToRadioPacket(meshtastic_MeshPacket &p)
 /// If the mesh service tells us fromNum has changed, tell the phone
 int PhoneAPI::onNotify(uint32_t newValue)
 {
-    checkConnectionTimeout(); // a handy place to check if we've heard from the phone (since the BLE version doesn't call this
-                              // from idle)
+    bool timeout = checkConnectionTimeout(); // a handy place to check if we've heard from the phone (since the BLE version
+                                             // doesn't call this from idle)
 
     if (state == STATE_SEND_PACKETS) {
         LOG_INFO("Telling client we have new packets %u\n", newValue);
@@ -471,5 +473,5 @@ int PhoneAPI::onNotify(uint32_t newValue)
         LOG_DEBUG("(Client not yet interested in packets)\n");
     }
 
-    return 0;
+    return timeout ? -1 : 0; // If we timed out, MeshService should stop iterating through observers as we just removed one
 }