Return empty string on UTF8 conversion with U_STRING_NOT_TERMINATED_WARNING error

changelogs/unreleased/fix-encoding-issue.yml

+---
+title: Fix encoding issue exporting a project
+merge_request:
+author:

lib/gitlab/git/encoding_helper.rb

@@ -40,7 +40,13 @@ module Gitlab
       def encode_utf8(message)
         detect = CharlockHolmes::EncodingDetector.detect(message)
         if detect
-          CharlockHolmes::Converter.convert(message, detect[:encoding], 'UTF-8')
+          begin
+            CharlockHolmes::Converter.convert(message, detect[:encoding], 'UTF-8')
+          rescue ArgumentError => e
+            Rails.logger.warn("Ignoring error converting #{detect[:encoding]} into UTF8: #{e.message}")
+
+            ''
+          end
         else
           clean(message)
         end

spec/lib/gitlab/git/encoding_helper_spec.rb

@@ -56,6 +56,10 @@ describe Gitlab::Git::EncodingHelper do
         expect(r.encoding.name).to eq('UTF-8')
       end
     end
+
+    it 'returns empty string on conversion errors' do
+      expect { ext_class.encode_utf8('') }.not_to raise_error(ArgumentError)
+    end
   end
 
   describe '#clean' do