Validate uniqueness of export keys

lib/quby/compiler/services/definition_validator.rb

@@ -81,8 +81,8 @@ module Quby
             fail "Score label langer dan 100 tekens (geeft problemen oru accare)\n #{score_schema.label}" if score_schema.label&.length > 100
           end
 
-          export_keys = questionnaire.score_schemas.flat_map { |key, score_schema|
-            score_schema.subscore_schemas.map {|subscore_schema| subscore_schema.export_key }
+          export_keys = questionnaire.score_schemas.flat_map { |_key, score_schema|
+            score_schema.subscore_schemas.map(&:export_key)
           }
 
           duplicate_export_keys = export_keys.tally.select { |key, count| count > 1 }.keys