kicad-cli: correctly label non-existent fields

Fixes: https://gitlab.com/kicad/code/kicad/-/issues/16085

eeschema/eeschema_jobs_handler.cpp

@@ -456,10 +456,12 @@ int EESCHEMA_JOBS_HANDLER::JobExportBom( JOB* aJob )
             field.groupBy = std::find( aBomJob->m_fieldsGroupBy.begin(),
                                        aBomJob->m_fieldsGroupBy.end(), field.name )
                             != aBomJob->m_fieldsGroupBy.end();
-            field.label = ( ( aBomJob->m_fieldsLabels.size() > i )
-                            && !aBomJob->m_fieldsLabels[i].IsEmpty() )
-                                  ? aBomJob->m_fieldsLabels[i]
-                                  : field.name;
+            if( ( aBomJob->m_fieldsLabels.size() > i ) && !aBomJob->m_fieldsLabels[i].IsEmpty() )
+                field.label = aBomJob->m_fieldsLabels[i];
+            else if( IsTextVar( field.name ) )
+                field.label = GetTextVars( field.name );
+            else
+                field.label = field.name;
 
             preset.fieldsOrdered.emplace_back( field );
             i++;

kicad/cli/command_sch_export_bom.cpp

@@ -158,6 +158,13 @@ int CLI::SCH_EXPORT_BOM_COMMAND::doPerform( KIWAY& aKiway )
             convertStringList( From_UTF8( m_argParser.get<std::string>( ARG_FIELDS ).c_str() ) );
     bomJob->m_fieldsLabels =
             convertStringList( From_UTF8( m_argParser.get<std::string>( ARG_LABELS ).c_str() ) );
+
+    // We only apply the default labels if the default fields are used
+    if( m_argParser.is_used( ARG_FIELDS ) && !m_argParser.is_used( ARG_LABELS ) )
+    {
+        bomJob->m_fieldsLabels.clear();
+    }
+
     bomJob->m_fieldsGroupBy =
             convertStringList( From_UTF8( m_argParser.get<std::string>( ARG_GROUP_BY ).c_str() ) );
     bomJob->m_sortField = From_UTF8( m_argParser.get<std::string>( ARG_SORT_FIELD ).c_str() );