Fix Error 500 when attempting to sort merge requests by weight

Fixes #673

app/finders/issuable_finder.rb

@@ -295,7 +295,8 @@ class IssuableFinder
   end
 
   def weights?
-    params[:weight].present? && params[:weight] != Issue::WEIGHT_ALL
+    params[:weight].present? && params[:weight] != Issue::WEIGHT_ALL &&
+      klass.column_names.include?('weight')
   end
 
   def filter_by_no_weight?

spec/finders/issues_finder_spec.rb

@@ -34,6 +34,22 @@ describe IssuesFinder do
         expect(issues).to contain_exactly(issue1, issue2, issue3)
       end
 
+      context 'sort by issues with no weight' do
+        let(:params) { { weight: Issue::WEIGHT_NONE } }
+
+        it 'returns all issues' do
+          expect(issues).to contain_exactly(issue1, issue2, issue3)
+        end
+      end
+
+      context 'sort by issues with any weight' do
+        let(:params) { { weight: Issue::WEIGHT_ANY } }
+
+        it 'returns all issues' do
+          expect(issues).to be_empty
+        end
+      end
+
       context 'filtering by assignee ID' do
         let(:params) { { assignee_id: user.id } }
 

spec/finders/merge_requests_finder_spec.rb

@@ -29,5 +29,11 @@ describe MergeRequestsFinder do
       merge_requests = MergeRequestsFinder.new(user, params).execute
       expect(merge_requests.size).to eq(1)
     end
+
+    it 'should ignore sorting by weight' do
+      params = { project_id: project1.id, scope: 'authored', state: 'opened', weight: Issue::WEIGHT_ANY }
+      merge_requests = MergeRequestsFinder.new(user, params).execute
+      expect(merge_requests.size).to eq(1)
+    end
   end
 end