if device goes away at just the right time, user won't be able to set channel

app/src/main/java/com/geeksville/mesh/MainActivity.kt

@@ -646,7 +646,16 @@ class MainActivity : AppCompatActivity(), Logging,
                 }
                 .setPositiveButton(R.string.accept) { _, _ ->
                     debug("Setting channel from URL")
+                    try {
                         model.setChannel(channel.settings)
+                    } catch (ex: RemoteException) {
+                        errormsg("Couldn't change channel ${ex.message}")
+                        Toast.makeText(
+                            this,
+                            "Couldn't change channel, because radio is not yet connected. Please try again.",
+                            Toast.LENGTH_SHORT
+                        ).show()
+                    }
                 }
                 .show()
         }