local set-up following README doesn't make success

[16dango]

Hi, I'm new to contribute on OSS.

I'd like to work on this
#1264

I'd like to join your project "lobsters" and started preparing local develop environment yesterday.
I followed all of README for that but I'm struggling on this step

rails fake_data

the error comes up like below

KeyError (key not found: :Field
Did you mean?  :"Field\x00\x00"):

app/models/keystore.rb:18:in `value_for'
app/helpers/traffic_helper.rb:59:in `cached_current_intensity'
app/controllers/application_controller.rb:109:in `set_traffic_style'

Is this because of my missed set-up on local or not.
Thank you.