[DevTools] Named hooks error badge

[bvaughn]

The named hooks cache returns Array<string | null> | null The first (mixed array of string and null) indicates an overall success, even if some names couldn't be inferred. The second indicates an error (e.g. couldn't locate or load source map).

In the event of the 2nd response type, the UI currently does nothing (falls back to default) but we should show an error badge (maybe a disabled but red icon with a tooltip saying there was an error) since it's a confusing user experience to just do nothing.