before miaou_debug auto-hierarchy

poc

@@ -229,8 +229,10 @@ function on_exit {
   trap - RETURN
   local code="${1:-0}" last_error regex
 
-  mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
-  2>&3 >&3 dump_stderr
+  miaou_debug "<on_exit code=$code>"
+
+  [[ ! -v tmp_error ]] && mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
+
   if [[ -v failure_type && "$failure_type" == 'RETURN' ]]; then
     last_error="${tmp_error[-1]}"
     regex='^(.*): line ([0-9]+): miaou_error: RETURN [0-9]+'
@@ -249,7 +251,7 @@ function on_exit {
   else
     if [[ $code -gt 0 && ${#tmp_error[@]} -gt 0 ]]; then
       last_error="${tmp_error[-1]}"
-      miaou_debug "<on_exit exit=$code last_error='$last_error'>"
+      miaou_debug "<on_exit_tmp_error last='$last_error'>"
       if [[ $code -eq 1 ]]; then
         regex='^(.*): line ([0-9]+): (.*): unbound variable$'
         if [[ "$last_error" =~ $regex ]]; then
@@ -272,16 +274,20 @@ function on_exit {
           error_funcname=("${error_funcname[@]}" '<main>')
         fi
       fi
+      miaou_debug "</on_exit_tmp_error>"
     fi
-    miaou_debug "</on_exit>"
   fi
 
-  if [[ $code -gt 0 && -v failure_type ]]; then
+  2>&3 >&3 dump_stderr
+  if [[ -v failure_type ]]; then
     2>&3 >&4 dump_failure
     2>&3 >&4 dump_stacktrace
   fi
-
-  miaou_debug "</source type=failure exit=$code pid=${BASHPID}>"
+  if [[ $code -gt 0 ]]; then
+    miaou_debug "</on_exit exit=$code>"
+  else
+    miaou_debug "</on_exit success>"
+  fi
 }
 
 ## main
@@ -301,7 +307,6 @@ trap 'on_return' RETURN
 if [[ -e /proc/$$/fd/3 ]]; then exec 4>&3 3>&-; else exec 4>/dev/tty; fi # swap fd 3 4 when fd 3 sent off
 exec 3>/dev/stderr 2>"$MIAOU_BASH_ERROR"
 
-miaou_debug "<source from=$BASH_ARGV0 pid=${BASHPID}>"
+miaou_debug "<source from=$BASH_ARGV0 pid=${BASHPID} />"
 # shellcheck source=/dev/null
 source "$BASH_ARGV0"
-miaou_debug "</source type=success pid=${BASHPID}>"