refactor i18n yaml to prevent overwriting parent non-English YAML with local English file: metanorma/isodoc#549

Author: opoudjis

lib/isodoc/iso/i18n.rb

@@ -2,8 +2,8 @@ module IsoDoc
   module Iso
     class I18n < IsoDoc::I18n
       def load_file(fname)
-        YAML.load_file(File.join(File.dirname(__FILE__), fname)) ||
-          {}
+        f = File.join(File.dirname(__FILE__), fname)
+        File.exist?(f) ? YAML.load_file(f) : {}
       end
 
       def load_yaml1(lang, script)

lib/isodoc/iso/presentation_bibdata.rb

@@ -73,10 +73,10 @@ def bibdata_i18n(bib)
       def bibdata_i18n_stage(bib, stage, type, lang: @lang, i18n: @i18n)
         return unless stage
 
-        i18n.get["stage_dict"][stage.text].is_a?(Hash) or
+        i18n.get.dig("stage_dict", stage.text).is_a?(Hash) or
           return hash_translate(bib, i18n.get["stage_dict"],
                                 "./status/stage", lang)
-        stagetype = i18n.get["stage_dict"][stage.text][type&.text] and
+        stagetype = i18n.get.dig("stage_dict", stage.text, type&.text) and
           tag_translate(stage, lang, stagetype)
       end
     end

spec/isodoc/i18n_spec.rb

@@ -549,17 +549,15 @@
           <bibdata>
            <status>
              <stage abbreviation='IS' language=''>60</stage>
-             <stage abbreviation='IS' language='tlh'>International Standard</stage>
            </status>
            <language current='true'>tlh</language>
            <ext>
              <doctype language=''>international-standard</doctype>
-             <doctype language='tlh'>International Standard</doctype>
            </ext>
          </bibdata>
           <preface>
             <clause type="toc" id="_" displayorder="1">
-              <title depth="1">Contents</title>
+              <title depth="1">Table of contents</title>
             </clause>
             <foreword obligation="informative" displayorder='2'>
               <title>Foreword</title>