No sanity check to see if all the required fields exists in the filters YAML file

[love-bhardwaj]

The filter file(.yml file) should have specific required fields for snyk-filter to work correctly. These are "customFilters", "filter", "pass" and "msg". If there is a typo in any of these snyk-filter throws a type error like below:

/Users/lovebhardwaj/Tools/snyk-filter/lib/snyk-filter.js:18
  const jqFilterString = customFilters.filter;
                                       ^

TypeError: Cannot read property 'filter' of undefined

The error is ambiguous for the user. We need to have sanity( ! == null) check to see if the required fields exist in the .yml file. If not then throw an error to let the user know.

    var ymlFileInJSON = yaml.safeLoad(fs.readFileSync(filters, 'utf8'));
    customFilters = ymlFileInJSON.customFilters; 

The YAML filter file used is attached for two different cases where same error is thrown(have changed the extension from .yml to .txt since GitHub won't let me attach a .yml file). First case the problem seems to be causes by indentation and second seems to be caused by incorrect field name.

Command used:

snyk-filter -i snyk_results.json -f snyk-filter-1.yml

snyk-filter-1.txt

snyk-filter-2.txt