That's interesting - I haven't seen errors in quite a while (on Firefox), and I've been using it myself for a few months. What are you doing just before it crashes?
I believe it first happened after cleaning the demo to start from zero. But the apps is quite buggy in other ways. For instance, trying to add the GBP currency fails silently, but it's apparently due to using a free API?
> "The *demo* API key is for demo purposes only. Please claim your free API key at (https://www.alphavantage.co/support/#api-key) to explore our full API offerings. It takes fewer than 20 seconds."
That's right - without a backend server, I couldn't think of a great way to manage a private API key. That means that users have to sign up for their own keys (instructions on the "Currency Sync" page under "Settings") if they want to use currency sync.
I thought I'd added a description to the error you get if you're still using the default "demo" key - clearly not, I'll add that it.
