pb.lua:198: attempt to concatenate a nil value (local 'article_body')
stack traceback:
  pb.lua:198: in main chunk
  [C]: in function 'xpcall'
  /usr/local/share/lua/5.3/cgilua.lua:181: in function 'cgilua.pcall'
  (...tail calls...)
  [C]: in function 'xpcall'
  /usr/local/share/lua/5.3/cgilua.lua:181: in function 'cgilua.pcall'
  /usr/local/share/lua/5.3/cgilua.lua:641: in function 'cgilua.main'
  /usr/local/share/lua/5.3/wsapi/sapi.lua:56: in function 'wsapi.sapi.run'
  (...tail calls...)
  [C]: in function 'xpcall'
  /usr/local/share/lua/5.3/wsapi/common.lua:270: in function 'wsapi.common.run_app'
  /usr/local/share/lua/5.3/wsapi/common.lua:297: in function 'wsapi.common.run'
  /usr/local/share/lua/5.3/wsapi/cgi.lua:19: in function 'wsapi.cgi.run'
  /usr/local/lib/luarocks/rocks/cgilua/5.2.1-1/bin/cgilua.cgi:21: in main chunk
  [C]: in ?