diff --git a/poc b/poc
index 428ecdb..a817402 100755
--- a/poc
+++ b/poc
@@ -49,20 +49,23 @@ function is_true {
 # example: alias toto="bash -c \"[[ \\\$MIAOU_DEBUG == 'true' ]] && echo yes \\\$* || echo nope\""
 function miaou_debug {
   if is_true "${MIAOU_DEBUG}"; then
+    local i message="$*" padding=''
     local compute_hierarchy=true
     [[ ! -v miaou_debug_hierarchy ]] && miaou_debug_hierarchy=0
-    local i message="$*" padding=''
+
     regex='^</' # starts with </
     [[ $miaou_debug_hierarchy -gt 0 ]] &&
       [[ "${message}" =~ $regex ]] &&
-      ((--miaou_debug_hierarchy)) &&
+      miaou_debug_hierarchy=$((miaou_debug_hierarchy - 1)) &&
       compute_hierarchy=false
+
     for ((i = 0; i < miaou_debug_hierarchy; i++)); do padding+='  '; done
     >&4 builtin echo -e "\e[90m <== DEBUG ==> ${padding}\e[33m${message}\e[0m"
+
     regex='[^/]>$' # does NOT end with />
     is_true $compute_hierarchy &&
       [[ "${message}" =~ $regex ]] &&
-      ((++miaou_debug_hierarchy)) ||
+      miaou_debug_hierarchy=$((miaou_debug_hierarchy + 1)) ||
       true
   fi
 }
@@ -117,7 +120,15 @@ function print_miaou_error {
   local message
   message="${source}: line ${line}: miaou_error: ${type} ${code}"
   [[ -n "$payload" ]] && message+=" payload: ${payload}"
-  [[ -v tmp_error ]] && miaou_debug "tmp_error=${#tmp_error[@]}" && tmp_error+=("$message") || >&2 echo "$message"
+  >&2 echo "$message"
+}
+
+function add_miaou_error {
+  local source="$1" line="$2" code="$3" type="$4" payload="${5:-}"
+  local message
+  message="${source}: line ${line}: miaou_error: ${type} ${code}"
+  [[ -n "$payload" ]] && message+=" payload: ${payload}"
+  tmp_error+=("$message")
 }
 
 function on_error {
@@ -131,11 +142,28 @@ function on_error {
     if [[ ! -v failure_type ]]; then
       if [[ ${BASH_COMMAND} == 'false' ]]; then
         failure_type="FALSE"
+        print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}"
       else
         failure_type="COMMAND_ERROR"
         failure_payload="${BASH_COMMAND}"
+        print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
+
+        miaou_debug "<investigate_tmp_error pid=${BASHPID}>"
+        load_tmp_error # cannot print_miaou_error after investigation
+
+        if [[ ${#tmp_error[@]} -gt 1 ]]; then
+          local last_error regex
+          last_error="${tmp_error[-2]}" # the second latest cause previous print_miaou_error above
+
+          regex='^(.*): line ([0-9]+): (.*): command not found$'
+          if [[ $failure_code == 127 && "$last_error" =~ $regex ]]; then
+            failure_type='COMMAND_NOT_FOUND'
+            failure_payload="${BASH_REMATCH[3]}"
+            miaou_debug "<command_not_found payload=${failure_payload}/>"
+          fi
+        fi
+        miaou_debug '</investigate_tmp_error>'
       fi
-      print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}"
     fi
 
     error_source=("${BASH_SOURCE[@]}")
@@ -153,11 +181,10 @@ function on_error {
     else
       miaou_debug "</on_error exit=$failure_code type=${failure_type}>"
     fi
-
     builtin exit "$failure_code"
   else
-    miaou_debug "</on_error pipe=$failure_code sub_pid=$BASHPID pid=$$ command={${BASH_COMMAND}}>"
     print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" 'SUBSHELL_ERROR' "${BASH_COMMAND}"
+    miaou_debug "</on_error pipe=$failure_code sub_pid=$BASHPID pid=$$ command={${BASH_COMMAND}}>"
     kill -PIPE $$
   fi
 }
@@ -174,7 +201,7 @@ function on_pipe {
   unset 'error_source[-1]' 'error_lineno[-1]' 'error_funcname[-1]'
   unset 'error_source[-1]' 'error_lineno[-1]' 'error_funcname[-1]'
 
-  miaou_debug '<load_tmp_error/>' && mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
+  load_tmp_error
 
   last_error="${tmp_error[-1]}"
   regex='^(.*): line ([0-9]+): miaou_error: SUBSHELL_ERROR ([0-9]+) payload: (.*)$'
@@ -247,15 +274,24 @@ function dump_stacktrace {
   miaou_debug '</stacktrace>'
 }
 
+function load_tmp_error {
+  [[ -v tmp_error ]] && return 0
+
+  mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
+  local count=${#tmp_error[@]}
+  if [[ $count == 0 ]]; then
+    miaou_debug "<tmp_error empty/>"
+  else
+    miaou_debug "<tmp_error count=${count}/>"
+  fi
+}
+
 function on_exit {
   trap - RETURN
   local code="${1:-0}" last_error regex
-
   miaou_debug "<on_exit code=$code>"
 
-  [[ ! -v tmp_error ]] &&
-    miaou_debug '<load_tmp_error/>' &&
-    mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
+  load_tmp_error
 
   if [[ -v failure_type && "$failure_type" == 'RETURN' ]]; then
     last_error="${tmp_error[-1]}"
@@ -272,7 +308,7 @@ function on_exit {
       miaou_debug "<return type=unexpected/>"
     fi
 
-  else
+  elif [[ ! -v failure_type ]]; then
     if [[ $code -gt 0 && ${#tmp_error[@]} -gt 0 ]]; then
       last_error="${tmp_error[-1]}"
       miaou_debug "<investigate_tmp_error last={$last_error}>"
@@ -298,9 +334,10 @@ function on_exit {
         failure_type='UNBOUND_VARIABLE'
         failure_payload=$payload
 
-        print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
-        unset 'tmp_error[-2]' # replace previous last_error
+        add_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
         miaou_debug "<unbound_variable source=${source} line=${line} payload={${failure_payload}}/>"
+      else
+        failure_type='UNKNOWN ERROR'
       fi
       miaou_debug "</investigate_tmp_error>"
     fi
@@ -332,6 +369,8 @@ trap 'on_exit $?' EXIT
 trap 'on_pipe' PIPE
 trap 'on_return' RETURN
 
+declare -a tmp_error # to prevent loading multiple times
+
 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"
 
diff --git a/test/poc.test.bash b/test/poc.test.bash
index 8be33eb..45b2dc0 100755
--- a/test/poc.test.bash
+++ b/test/poc.test.bash
@@ -24,7 +24,7 @@ function fail_type {
   mapfile -t stderr <<<"$(./poc ./test/stub/scenario.bash "$1" 2>&1 >/dev/null 3>/dev/null)"
   last_error="${stderr[-1]}"
 
-  regex="^(.*): line ([0-9]+): miaou_error: $2 ([0-9]+) payload: (.*)\$"
+  regex="^(.*): line ([0-9]+): miaou_error: $2 ([0-9]+)"
   [[ "${last_error}" =~ $regex ]] && success=true
 
   # if [[ $success == true && -n "${hint_message}" ]]; then
@@ -60,13 +60,13 @@ fail_type command_not_found COMMAND_NOT_FOUND
 # fail_type subshell_error COMMAND_NOT_FOUND '(hint: prefer source than subshell)'
 # fail_type command_error COMMAND_ERROR
 
-failed=$((test_count - ${#failures[@]}))
+failed=${#failures[@]}
 success=$((test_count - failed))
 
 echo
 if [[ $failed -gt 0 ]]; then
   ratio=$((100 * success / test_count))
-  echo "${ratio}% passed, $success succeeded, $failed failed!"
+  echo "${ratio}% passed, ${test_count} tests, ${failed} failed!"
   echo failures:
   for failure in "${failures[@]}"; do
     echo -e "\t- $failure"