Do not propagate parsing exceptions to clients for `pipelineFindings`

ee/app/graphql/resolvers/pipeline_security_report_findings_resolver.rb

@@ -23,7 +23,12 @@ module Resolvers
              description: 'Filter vulnerability findings by state.'
 
     def resolve(**args)
+      # This finder class has been deprecated and will be removed by
+      # https://gitlab.com/gitlab-org/gitlab/-/issues/334488.
+      # We can remove the rescue block while addressing that issue.
       Security::PipelineVulnerabilitiesFinder.new(pipeline: pipeline, params: args).execute.findings
+    rescue Security::PipelineVulnerabilitiesFinder::ParseError
+      []
     end
   end
 end

ee/spec/graphql/resolvers/pipeline_security_report_findings_resolver_spec.rb

@@ -63,5 +63,17 @@ RSpec.describe Resolvers::PipelineSecurityReportFindingsResolver do
         expect(Security::PipelineVulnerabilitiesFinder).to have_received(:new).with(pipeline: pipeline, params: params)
       end
     end
+
+    context 'when the finder class raises parsing error' do
+      before do
+        allow_next_instance_of(Security::PipelineVulnerabilitiesFinder) do |finder|
+          allow(finder).to receive(:execute).and_raise(Security::PipelineVulnerabilitiesFinder::ParseError)
+        end
+      end
+
+      it 'does not propagate the error to the client' do
+        expect { resolve_query }.not_to raise_error
+      end
+    end
   end
 end