Elvis configuration errors are not correctly handled

[josephDunne]

Describe the bug
I get the following error in the erlang_ls server log while running on OTP 24:

[2021-07-30T16:52:56.742371+01:00] [warning] Background job aborted. [reason={function_clause,[{els_elvis_diagnostics,format_rules,["src/file.erl",[#{error_msg => "'~p' while applying rule '~p'.",info => [undef,line_length]}]],[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,68}]},{els_elvis_diagnostics,format_diagnostics,1,[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,62}]},{lists,flatmap,2,[{file,"lists.erl"},{line,1254}]},{els_background_job,handle_info,2,[{file,"src/erlang_ls/apps/els_lsp/src/els_background_job.erl"},{line,160}]},{gen_server,try_dispatch,4,[{file,"gen_server.erl"},{line,695}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,771}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,226}]}]}] [els_background_job:terminate/2 L196] <0.213.0>
[2021-07-30T16:52:56.757527+01:00] [error] Generic server <0.213.0> terminating. Reason: {function_clause,[{els_elvis_diagnostics,format_rules,["src/file.erl",[#{error_msg => "'~p' while applying rule '~p'.",info => [undef,line_length]}]],[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,68}]},{els_elvis_diagnostics,format_diagnostics,1,[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,62}]},{lists,flatmap,2,[{file,"lists.erl"},{line,1254}]},{els_background_job,handle_info,2,[{file,"src/erlang_ls/apps/els_lsp/src/els_background_job.erl"},{line,160}]},{gen_server,try_dispatch,4,[{file,"gen_server.erl"},{line,695}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,771}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,226}]}]}. Last message: exec. State: #{config => #{entries => [<<"file://src/file.erl">>],on_complete => #Fun<els_diagnostics.1.67775306>,on_error => #Fun<els_background_job.0.71521734>,task => #Fun<els_diagnostics.0.67775306>,title => <<"Elvis (file)">>},current => 0,internal_state => undefined,progress_enabled => true,show_percentages => true,spinning_wheel => undefined,step => 100.0,token => <<"297b1d81-706f-4d74-b76b-b635f87b861e">>,total => 1}. [gen_server:error_info/7 L949] <0.213.0>
[2021-07-30T16:52:56.758508+01:00] [error] crasher: initial call: els_background_job:init/1, pid: <0.213.0>, registered_name: [], error: {function_clause,[{els_elvis_diagnostics,format_rules,["src/file.erl",[#{error_msg => "'~p' while applying rule '~p'.",info => [undef,line_length]}]],[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,68}]},{els_elvis_diagnostics,format_diagnostics,1,[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,62}]},{lists,flatmap,2,[{file,"lists.erl"},{line,1254}]},{els_background_job,handle_info,2,[{file,"src/erlang_ls/apps/els_lsp/src/els_background_job.erl"},{line,160}]},{gen_server,try_dispatch,4,[{file,"gen_server.erl"},{line,695}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,771}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,226}]}]}, ancestors: [els_background_job_sup,els_sup,<0.157.0>], message_queue_len: 1, messages: [{'EXIT',<0.416.0>,normal}], links: [<0.179.0>], dictionary: [], trap_exit: true, status: running, heap_size: 75113, stack_size: 29, reductions: 4846283; neighbours: [proc_lib:crash_report/4 L525] <0.213.0>
[2021-07-30T16:52:56.759133+01:00] [error] Supervisor: {local,els_background_job_sup}. Context: child_terminated. Reason: {function_clause,[{els_elvis_diagnostics,format_rules,["src/file.erl",[#{error_msg => "'~p' while applying rule '~p'.",info => [undef,line_length]}]],[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,68}]},{els_elvis_diagnostics,format_diagnostics,1,[{file,"src/erlang_ls/apps/els_lsp/src/els_elvis_diagnostics.erl"},{line,62}]},{lists,flatmap,2,[{file,"lists.erl"},{line,1254}]},{els_background_job,handle_info,2,[{file,"src/erlang_ls/apps/els_lsp/src/els_background_job.erl"},{line,160}]},{gen_server,try_dispatch,4,[{file,"gen_server.erl"},{line,695}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,771}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,226}]}]}. Offender: id=els_background_job,pid=<0.213.0>. [supervisor:do_restart/3 L751] <0.179.0>

looks like a function clause in els_elvis_diagnostics to do with the change in line lengths in the compiler

To Reproduce
Use the language server with OTP 24 on any erlang file

Context

• erlang_ls version (tag/sha): 35efe6e
• Editor used: vscode
• LSP client used: vscode

[robertoaloi]

Hi @josephDunne and thanks for the report!

I believe this is not an OTP 24 specific issue. What you are experiencing seems to be the combination of two issues:

1. elvis_core was recently updated in a backward-incompatible manner and your elvis.config still follows the old format. To fix your config, simply replace {elvis_style, line_length... with {elvis_text_style, line_length. You can also check here the full migration guide for Elvis.

2. Erlang LS does not handle configuration errors correctly and crashes (as in your case). I will shortly push a fix so that config errors are treated as regular diagnostics.

[robertoaloi]

Closing as solved.