Mine

Debugger entered--Lisp error: (wrong-type-argument hash-table-p nil)
  gethash("pspp" nil)
  erc-button-add-nickname-buttons(((quote nicknames) 0 erc-button-buttonize-nicks erc-nick-popup 0))
  erc-button-add-buttons()
  run-hooks(erc-insert-modify-hook)
  erc-display-line-1(#("*** #pspp modes: +tnc" 0 21 (rear-sticky t erc-parsed [cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ... "+tnc"] face erc-notice-face)) #<buffer #pspp>)
  erc-display-line(#("*** #pspp modes: +tnc" 0 21 (rear-sticky t erc-parsed [cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ... "+tnc"] face erc-notice-face)) #<buffer #pspp>)
  erc-display-message([cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ("jmd`" "#pspp" "+tnc") "+tnc"] notice #<buffer #pspp> s324 99 "#pspp" 109 "+tnc")
  erc-server-324(#<process erc-irc.freenode.net-6667> [cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ("jmd`" "#pspp" "+tnc") "+tnc"])
  run-hook-with-args-until-success(erc-server-324 #<process erc-irc.freenode.net-6667> [cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ("jmd`" "#pspp" "+tnc") "+tnc"])
  erc-call-hooks(#<process erc-irc.freenode.net-6667> [cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ("jmd`" "#pspp" "+tnc") "+tnc"])
  erc-handle-parsed-server-response(#<process erc-irc.freenode.net-6667> [cl-struct-erc-response ":brown.freenode.net 324 jmd` #pspp +tnc " "brown.freenode.net" "324" ("jmd`" "#pspp" "+tnc") "+tnc"])
  erc-parse-server-response(#<process erc-irc.freenode.net-6667> ":brown.freenode.net 324 jmd` #pspp +tnc ")
  erc-server-filter-function(#<process erc-irc.freenode.net-6667> ":brown.freenode.net PONG brown.freenode.net :1151495379\n")