raise error if hiera.yaml is specified but does not exist

lib/puppet-lint/plugins/check_ghostbuster_hiera_files.rb

@@ -14,10 +14,14 @@ def load_data(path, content)
 
 PuppetLint.new_check(:ghostbuster_hiera_files) do
   def hiera
-    @hiera ||= [ENV.fetch('HIERA_YAML_PATH', nil), '/etc/puppetlabs/puppetlabs/hiera.yaml'].filter_map do |hiera_file|
-      YAML.load_file(hiera_file) if hiera_file && File.exist?(hiera_file)
-    end
-    @hiera[0]
+    @hiera ||= if (hiera_file = ENV.fetch('HIERA_YAML_PATH', false))
+                 YAML.load_file(hiera_file)
+               else
+                 hiera = ['/etc/puppetlabs/puppet/hiera.yaml'].filter_map do |hf|
+                   YAML.load_file(hf) if hf && File.exist?(hf)
+                 end
+                 hiera[0]
+               end
   end
 
   def default_datadir

spec/puppet-lint/plugins/ghostbuster_hiera_files_spec.rb

@@ -109,5 +109,14 @@
         expect(problems.size).to eq(0)
       }
     end
+
+    context 'when HIERA_YAML_PATH is set but does not exist' do
+      let(:path) { './data/domain/example.com.yaml' }
+
+      it {
+        ENV['HIERA_YAML_PATH'] = './spec/fixtures/j.yaml'
+        expect { problems }.to raise_error(Errno::ENOENT)
+      }
+    end
   end
 end