fix(client): set useSession loading state correctly (#1468)

This is fixing #1467.

The issue was due to doing the `setLoading(false)` in the finally:  as we can do an early return [here](a7e08e2a32/src/client/index.js (L100-L100)), we would still go to the finally and mark the session as being loaded.

I simply removed the `finally` block to only set the `loading` state to false when:
- the data is ready
- an error occures

src/client/index.js

@@ -130,9 +130,9 @@ function _useSessionHook (session) {
         __NEXTAUTH._clientSession = newClientSessionData
 
         setData(newClientSessionData)
+        setLoading(false)
       } catch (error) {
         logger.error('CLIENT_USE_SESSION_ERROR', error)
-      } finally {
         setLoading(false)
       }
     }