UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.86 Safari/537.36

Steps to reproduce the problem:
1. go to https://gerrit-review.googlesource.com/c/79116/ with PG on.

2. page stuck on "loading".

3. observe type errors in console

What is the expected behavior?

What went wrong?
gr-app.js:28210 Uncaught TypeError: Cannot read property '_number' of undefinedPolymer._computeLatestPatchNum @ gr-app.js:28210Polymer.Base.extend._annotatedComputationEffect @ gr-app.js:4460Polymer.Bind._modelApi._effectEffects @ gr-app.js:4267Polymer.Bind._modelApi._propertySetter @ gr-app.js:4251Polymer.Bind._modelApi.__setProperty @ gr-app.js:4260Polymer.Templatizer.__setPropertyImpl @ gr-app.js:6594Polymer.Base._addFeature._applyConfig @ gr-app.js:4869Polymer.Base._addFeature._afterClientsReady @ gr-app.js:4863Polymer.Base._addFeature._ready @ gr-app.js:806Polymer.Base._addFeature._tryReady @ gr-app.js:792Polymer.Templatizer._constructorImpl @ gr-app.js:6752TemplateInstance @ gr-app.js:6556Polymer.Templatizer.stamp @ gr-app.js:6781Polymer._stampInstance @ gr-app.js:7312Polymer._insertInstance @ gr-app.js:7320Polymer._applyFullRefresh @ gr-app.js:7184Polymer._render @ gr-app.js:7116Debouncer.complete @ gr-app.js:2817boundComplete @ gr-app.js:2794Polymer.Async._atEndOfMicrotask @ gr-app.js:2772window.MutationObserver.observe.characterData @ gr-app.js:2787
gr-app.js:28188 Uncaught (in promise) TypeError: Cannot read property '_number' of undefined(…)Polymer._changeChanged @ gr-app.js:28188Polymer.Base.extend._observerEffect @ gr-app.js:4424Polymer.Bind._modelApi._effectEffects @ gr-app.js:4267Polymer.Bind._modelApi._propertySetter @ gr-app.js:4251setter @ gr-app.js:4330(anonymous function) @ gr-app.js:28337

gr-app.js:28188 Uncaught (in promise) TypeError: Cannot read property '_number' of undefined(…)Polymer._changeChanged @ gr-app.js:28188Polymer.Base.extend._observerEffect @ gr-app.js:4424Polymer.Bind._modelApi._effectEffects @ gr-app.js:4267Polymer.Bind._modelApi._propertySetter @ gr-app.js:4251setter @ gr-app.js:4330(anonymous function) @ gr-app.js:28337

Did this work before? N/A 

Chrome version: 50.0.2661.86  Channel: n/a
OS Version: 
Flash Version: Shockwave Flash 21.0 r0