TypeError while dumping messages

[Grigoriy0]

Sometimes (often) in chats/groups I got error:

Traceback (most recent call last):
        16: from telegram-history-dump.rb:375:in `<main>'
        15: from telegram-history-dump.rb:375:in `each_with_index'
        14: from telegram-history-dump.rb:375:in `each'
        13: from telegram-history-dump.rb:379:in `block in <main>'
        12: from telegram-history-dump.rb:78:in `dump_dialog'
        11: from telegram-history-dump.rb:78:in `loop'
        10: from telegram-history-dump.rb:91:in `block in dump_dialog'
         9: from /usr/lib/ruby/2.5.0/timeout.rb:108:in `timeout'
         8: from /usr/lib/ruby/2.5.0/timeout.rb:33:in `catch'
         7: from /usr/lib/ruby/2.5.0/timeout.rb:33:in `catch'
         6: from /usr/lib/ruby/2.5.0/timeout.rb:33:in `block in catch'
         5: from /usr/lib/ruby/2.5.0/timeout.rb:93:in `block in timeout'
         4: from telegram-history-dump.rb:92:in `block (2 levels) in dump_dialog'
         3: from telegram-history-dump.rb:48:in `exec_tg_command'
         2: from /usr/lib/ruby/2.5.0/json/common.rb:156:in `parse'
         1: from /usr/lib/ruby/2.5.0/json/common.rb:156:in `new'
/usr/lib/ruby/2.5.0/json/common.rb:156:in `initialize': no implicit conversion of nil into String (TypeError)

I do not know what type of messages this happens to, but I opened issue. I think, that I am not only one with this problem. Well, what if someone finds a solution?

[Arunm0111986]

Need help