Uncaught TypeError: Cannot read property 'gcsUrl' of null

[danicorc]

Once I follow all the steps of Github tutorial for instalation of Vision API demo. Brings me this error:
Uncaught TypeError: Cannot read property 'gcsUrl' of null
at main.js:308
at firebase-database.js:193
at fc (firebase-database.js:57)
at bf (firebase-database.js:122)
at cf (firebase-database.js:121)
at Object.G (firebase-database.js:211)
at firebase-database.js:171
at Ag.g.wd (firebase-database.js:176)
at og.wd (firebase-database.js:166)
at Uf.te (firebase-database.js:164)