TrailDBConstructor crashes if the first field is called username

[rhymes]

I don't know why but it seems to me that TrailDBConstructor crashes if the first fieldname is username:

Python 2.7.13 (default, May 2 2017, 15:58:16) [GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.42)] on darwin Type "help", "copyright", "credits" or "license" for more information.

from traildb import TrailDBConstructor, TrailDB cons = TrailDBConstructor('foobar', ['username']) [1] 88728 abort python

I noticed it because I was going through the tutorial and the first example didn't work http://traildb.io/docs/tutorial/#part-i-create-a-simple-traildb

I noticed that it doesn't happen if the field called "username" is not the first item in the array:

from traildb import TrailDBConstructor TrailDBConstructor('foobar', ['alice', 'username']) <traildb.traildb.TrailDBConstructor object at 0x10f609450>