Do not process new Ci config entry when invalid

lib/gitlab/ci/config/node/entry.rb

@@ -16,10 +16,14 @@ module Gitlab
             keys.each_key do |key|
               instance_variable_set("@#{key}", Null.new(nil, root, self))
             end
+
+            unless leaf? || value.is_a?(Hash)
+              @errors << 'should be a configuration entry with hash value'
+            end
           end
 
           def process!
-            return if leaf?
+            return if leaf? || !valid?
 
             keys.each do |key, entry_class|
               next unless @value.has_key?(key)
@@ -42,7 +46,7 @@ module Gitlab
           end
 
           def leaf?
-            keys.none? # TODO || !@value.is_a?(Hash)
+            keys.none?
           end
 
           def keys

spec/lib/gitlab/ci/config/node/global_spec.rb

@@ -58,4 +58,16 @@ describe Gitlab::Ci::Config::Node::Global do
       end
     end
   end
+
+  context 'when value is not a hash' do
+    let(:hash) { [] }
+
+    before { global.process! }
+
+    describe '#valid?' do
+      it 'is not valid' do
+        expect(global).not_to be_valid
+      end
+    end
+  end
 end