Unchecked error when a feature is not named.

[mgalbis]

When a feature is created and has no keyword description, an unhandled error is thrown. E.g.:

• This fails:

  Feature: 
  
  Scenario: A
  ...

• This does not fail:

  Feature: Some descripcion
  
  Scenario: A
  ...

It should be checked that it contains a description in the gherkin parser.