frontend/summary,account: sdcard check false positive

If one inserts a BitBox02 while in the account summary or account,
`useSDCard(devices);` returns true even if there is no sdcard,
because:

1. It is called before the BitBox02 has established the
communication (paired channel)
2. The checkSDCard endpoints returns an error
3. The `useSDCard()` assumes the result is `boolean` always, so it
interprets the non-zero error as `true`, which leads to the warning
banner being shown even if the sdcard is not inserted.

This is a quick fix to not show the banner in this case by returning
`false` instead of an error.

The proper fix is postponed, and involes rewriting `useSDCard` to
listen on the `statusChanged` event of the BitBox02 to only chekc the
sdcard once the device is paired (or do something similar in the
backend and make an `sdcard` event).

Author: benma

backend/devices/bitbox02/handlers/handlers.go

@@ -261,7 +261,7 @@ func (handlers *Handlers) getCheckSDCard(_ *http.Request) interface{} {
 	handlers.log.Debug("Checking if SD Card is inserted")
 	sdCardInserted, err := handlers.device.CheckSDCard()
 	if err != nil {
-		return maybeBB02Err(err, handlers.log)
+		return false
 	}
 	return sdCardInserted
 }