rem: text_comparison -> text = g_strdup (last_text_comparison -> text);
add: if (last_text_comparison -> text) text_comparison -> text = g_strdup (last_text_comparison -> text);
context: gint gsb_data_report_text_comparison_dup ( gint last_text_comparison_number ){    struct_text_comparison *text_comparison;    struct_text_comparison *last_text_comparison;    gint text_comparison_number;        last_text_comparison = gsb_data_report_text_comparison_get_struct_by_no (last_text_comparison_number);    if ( !last_text_comparison )	return 0;    text_comparison_number = gsb_data_report_text_comparison_new (0);    text_comparison = gsb_data_report_text_comparison_get_struct_by_no (text_comparison_number);    text_comparison -> report_number = last_text_comparison -> report_number;    text_comparison -> link_to_last_text_comparison = last_text_comparison -> link_to_last_text_comparison;    text_comparison -> field = last_text_comparison -> field;    text_comparison -> operator = last_text_comparison -> operator;    text_comparison -> text = g_strdup (last_text_comparison -> text);    text_comparison -> use_text = last_text_comparison -> use_text;    text_comparison -> first_comparison = last_text_comparison -> first_comparison;    text_comparison -> first_amount = last_text_comparison -> first_amount;    text_comparison -> link_first_to_second_part = last_text_comparison -> link_first_to_second_part;    text_comparison -> second_comparison = last_text_comparison -> second_comparison;    text_comparison -> second_amount = last_text_comparison -> second_amount;    return text_comparison_number;}