theia: Window is not defined error when starting theia backend

I’ve traced this to setRootLogger:

ReferenceError: window is not defined
    at Object.setRootLogger (/home/eantotr/sync/work/theia/packages/core/lib/common/logger.js:55:29)
    at Object.initialize (/home/eantotr/sync/work/theia/packages/core/lib/node/logger-backend-module.js:45:26)
    at new BackendApplication (/home/eantotr/sync/work/theia/packages/core/lib/node/backend-application.js:151:38)
    at _createInstance (/home/eantotr/sync/work/theia/node_modules/inversify/lib/resolution/instantiation.js:21:12)
    at Object.resolveInstance (/home/eantotr/sync/work/theia/node_modules/inversify/lib/resolution/instantiation.js:41:18)
    at /home/eantotr/sync/work/theia/node_modules/inversify/lib/resolution/resolver.js:72:42
    at Object.resolve (/home/eantotr/sync/work/theia/node_modules/inversify/lib/resolution/resolver.js:96:12)
    at /home/eantotr/sync/work/theia/node_modules/inversify/lib/container/container.js:245:37
    at Container._get (/home/eantotr/sync/work/theia/node_modules/inversify/lib/container/container.js:236:44)
    at Container.get (/home/eantotr/sync/work/theia/node_modules/inversify/lib/container/container.js:195:21)

@akosyakov could you take a look ?