map_bug.erl

%% Just happens in the shell afaik
1> lists:map(fun(X) -> X#{price := 0} end, [#{hello => 0, price => nil}]).
** exception error: no match of right hand side value #{hello => 0,price => nil}
     in function  erl_eval:expr/5 (erl_eval.erl, line 248)
     in call from lists:map/2 (lists.erl, line 1237)
2> (fun(X) -> X#{price := 0} end)(#{hello => 0, price => nil}).
#{hello => 0,price => 0}