Missing React key prop in Metadata.tsx

Seems to be triggered in the line: {hit.metadata.types.map(t => DatasetTypeBadge(t))}

index.js:1 Warning: Each child in a list should have a unique "key" prop.

Check the render method of `DatasetTypes`. See https://fb.me/react-warning-keys for more information.
    in span (at Badges.tsx:83)
    in DatasetTypes (at SearchHit.tsx:144)
    in div (at SearchHit.tsx:139)
    in div (at SearchHit.tsx:132)
    in SearchHit (at SearchResults.tsx:61)
    in div (at SearchResults.tsx:59)
    in div (at SearchResults.tsx:130)
    in div (at SearchResults.tsx:129)
    in SearchResults (at SearchApp.tsx:575)
    in div (at SearchApp.tsx:570)
    in div (at SearchApp.tsx:529)
    in SearchApp (at App.tsx:44)
    in Route (at App.tsx:39)
    in Switch (at App.tsx:14)
    in Router (created by BrowserRouter)
    in BrowserRouter (at App.tsx:13)
    in div (at App.tsx:12)
    in App (at src/index.tsx:9)