Fix

src/lager_logger_formatter.erl

@@ -22,7 +22,7 @@ report_cb(#{msg := {report, #{label := {Behaviour, no_handle_info}, mod := Mod,
 report_cb(#{label := {supervisor, progress}, report := Report}) ->
     case application:get_env(lager, suppress_supervisor_start_stop, false) of
         true ->
-            "";
+            {"", []};
         false ->
             {supervisor, Name} = lists:keyfind(supervisor, 1, Report),
             {started, Started} = lists:keyfind(started, 1, Report),
@@ -65,7 +65,7 @@ report_cb(#{label := {supervisor, _Error}, report := Report}) ->
     end;
 report_cb(#{label := {application_controller, progress}, report := Report}) ->
     case application:get_env(lager, suppress_application_start_stop, false) of
-        true -> "";
+        true -> {"", []};
         false ->
             {application, Name} = lists:keyfind(application, 1, Report),
             {started_at, Node} = lists:keyfind(started_at, 1, Report),
@@ -75,7 +75,7 @@ report_cb(#{label := {application_controller, exit}, report := Report}) ->
     {exited, Reason} = lists:keyfind(exited, 1, Report),
     case application:get_env(lager, suppress_application_start_stop) of
         {ok, true} when Reason == stopped ->
-            "";
+            {"", []};
         _ ->
             {application, Name} = lists:keyfind(application, 1, Report),
             {_Md, Formatted} = error_logger_lager_h:format_reason_md(Reason),
@@ -89,10 +89,7 @@ format(#{level := _Level, msg := {report, Report}, meta := #{report_cb := Fun}}
     case Fun(Report) of
         {"", []} -> "";
         {Format, Args} when is_list(Format), is_list(Args) ->
-            format(Event#{msg => {Format, Args}}, Config);
-        "" -> "";
-        String ->
-            format(Event#{msg => {string, String}}, Config)
+            format(Event#{msg => {Format, Args}}, Config)
     end;
 format(#{level := Level, msg := {string, String}, meta := Metadata}, Config) ->
     do_format(Level, String, Metadata, Config);