project cannot commit (ventureum in Rinkeby)

[b232wang]

In http://alpha.ventureum.io, when I try to commit a project after challenge, it shows following error.

Minified React error #31; visit http://reactjs.org/docs/error-decoder.html?invariant=31&args[]=object%20with%20keys%20%7Bs%2C%20e%2C%20c%7D&args[]= for the full message or use the non-minified dev environment for full errors and additional helpful warnings.

The console error:

react-dom.production.min.js:151 Error: Minified React error #31; visit http://reactjs.org/docs/error-decoder.html?invariant=31&args[]=object%20with%20keys%20%7Bs%2C%20e%2C%20c%7D&args[]= for the full message or use the non-minified dev environment for full errors and additional helpful warnings. 
    at r (invariant.js:42)
    at r (react-dom.production.min.js:14)
    at gt (react-dom.production.min.js:120)
    at react-dom.production.min.js:130
    at c (react-dom.production.min.js:131)
    at u (react-dom.production.min.js:131)
    at beginWork (react-dom.production.min.js:140)
    at a (react-dom.production.min.js:176)
    at o (react-dom.production.min.js:176)
    at w (react-dom.production.min.js:182)
    at y (react-dom.production.min.js:181)
    at g (react-dom.production.min.js:181)
    at d (react-dom.production.min.js:180)
    at l (react-dom.production.min.js:179)
    at Object.enqueueSetState (react-dom.production.min.js:110)
    at t.i.setState (react.production.min.js:12)