How to decipher Erlang runtime error message

Question

When I run an Erlang function using IntelliJ's "Run Configuration", I am getting the following error message. The error message contains lot of nested brackets. Please help me in understanding the message.

"C:\Program Files\Erlang OTP\bin\erl.exe" -pa F:/1TB/P/workspace-IntelliJ-Erlang2/netconfClient/out/production/netconfClient -pa F:/1TB/P/workspace-IntelliJ-Erlang2/netconfClient -eval netconfManager:open2(). -s init stop -noshell
init terminating in do_boot ({badarg,[{ets,select,[ct_attributes,[_]],[{_}]},{ct_config,get_key_from_name,1,[{_},{_}]},{ct_util,does_connection_exist,3,[{_},{_}]},{ct_gen_conn,do_start,4,[{_},{_}]},{ct_netconfc,open,4,[{_},{_}]},{erl_eval,do_apply,7,[{_},{_}]},{init,start_it,1,[{_},{_}]},{init,start_em,1,[{_},{_}]}]})

Crash dump is being written to: erl_crash.dump...{"init terminating in do_boot",{badarg,[{ets,select,[ct_attributes,[{{ct_conf,'$1','_','_','_',undefined,'_'},[],['$1']}]],[{error_info,#{cause=>id,module=>erl_stdlib_errors}}]},{ct_config,get_key_from_name,1,[{file,"ct_config.erl"},{line,578}]},{ct_util,does_connection_exist,3,[{file,"ct_util.erl"},{line,577}]},{ct_gen_conn,do_start,4,[{file,"ct_gen_conn.erl"},{line,281}]},{ct_netconfc,open,4,[{file,"ct_netconfc.erl"},{line,424}]},{erl_eval,do_apply,7,[{file,"erl_eval.erl"},{line,744}]},{init,start_it,1,[{file,"init.erl"},{line,1234}]},{init,start_em,1,[{file,"init.erl"},{line,1220}]}]}}
done

Right click on a function in a .erl file and click on "Run ."

Answer 1

The error message consists of Error code and Stack trace.

1. Error code is badarg. Please refer to Exit Reasons for the list of error code.
2. The stack trace contains one entry for each function call. Each call provides file name, function name, line number. For example, {init,start_em,1,[{file,"init.erl"},{line,1220}]} indicates that init.erl is the file, start_em is the function and 1220 is line #.

After manual indentation, we could better visualize the stacktrace as follows.

{badarg,[
{ets,select,[ct_attributes,[_]],[{_}]},
{ct_config,get_key_from_name,1,[{_},{_}]},
{ct_util,does_connection_exist,3,[{_},{_}]},
{ct_gen_conn,do_start,4,[{_},{_}]},
{ct_netconfc,open,4,[{_},{_}]},
{erl_eval,do_apply,7,[{_},{_}]},
{init,start_it,1,[{_},{_}]},
{init,start_em,1,[{_},{_}]}
]}

{badarg,[
{ets,select,[ct_attributes,[{{ct_conf,'$1','_','_','_',undefined,'_'},[],['$1']}]],[{error_info,#{cause=>id,module=>erl_stdlib_errors}}]},
{ct_config,get_key_from_name,1,[{file,"ct_config.erl"},{line,578}]},
{ct_util,does_connection_exist,3,[{file,"ct_util.erl"},{line,577}]},
{ct_gen_conn,do_start,4,[{file,"ct_gen_conn.erl"},{line,281}]},
{ct_netconfc,open,4,[{file,"ct_netconfc.erl"},{line,424}]},
{erl_eval,do_apply,7,[{file,"erl_eval.erl"},{line,744}]},
{init,start_it,1,[{file,"init.erl"},{line,1234}]},
{init,start_em,1,[{file,"init.erl"},{line,1220}]}
]}