Cannot apply @injectable decorator multiple times

I have encountered this problem many times

Failed to start the frontend application.
(anonymous) @ bundle.js:2
Promise.catch (async)
(anonymous) @ bundle.js:2
Promise.then (async)
37614 @ bundle.js:2
i @ bundle.js:2
(anonymous) @ bundle.js:2
(anonymous) @ bundle.js:2
bundle.js:2 Error: Cannot apply @injectable decorator multiple times.
    at bundle.js:2:10628074
    at bundle.js:2:11426879
    at Reflect.<anonymous> (bundle.js:2:11426943)
    at s (bundle.js:2:10627055)
    at t.decorate (bundle.js:2:10627341)
    at 44474 (bundle.js:2:4192905)
    at i (bundle.js:2:15493325)
    at 62603 (bundle.js:2:4188991)
    at i (bundle.js:2:15493325)
    at 98202 (bundle.js:2:3807105)

Hey @wenqi,

this usually appears if you have multiple versions of Theia in your node_modules. You should pin all versions of Theia dependencies to a single version (e.g. 1.30).