generator.py fails silently if you specify an invalid --type

[fearful-symmetry]

For confirmed bugs, please report:

• Version: master
• Operating System: any
• Steps to Reproduce:

python ${GOPATH}/src/github.com/elastic/beats/script/generate.py --type=fakebeat --project_name=examplebeat

Since fakebeat doesn't exist, nothing happens. The script exits zero, no message is printed.

This is presumably because the python script is iterating over a directory that doesn't exist:

 for root, dirs, files in os.walk(template_path + '/' + beat_type + '/{beat}'):

According to the pydoc, os.walk will ignore errors by default. We should either specify some error handling for os.walk, or check the validity of the type before hand.

[fearful-symmetry]

Fix has been merged.