unbound_variable caught up

poc

@@ -127,7 +127,6 @@ function on_pipe {
 
 function dump_stderr {
   miaou_debug '<stderr>'
-  mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
   tty_ansi FG_LIGHTBLUE
   for i in "${tmp_error[@]}"; do echo "$i"; done
   tty_ansi RESET
@@ -179,14 +178,39 @@ function dump_stacktrace {
 }
 
 function on_exit {
+  local code
   code="${1:-0}"
 
+  mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
   2>&3 >&3 dump_stderr
-  # tmp_error already filled up through the dump_stderr call
+
   if [[ $code -gt 0 && ${#tmp_error[@]} -gt 0 ]]; then
-    local last_error
+    local last_error regex
     last_error="${tmp_error[-1]}"
-    miaou_debug "<on_exit exit=$code last_error='$last_error' />"
+    miaou_debug "<on_exit exit=$code last_error='$last_error'>"
+    if [[ $code -eq 1 ]]; then
+      regex='^(.*): line ([0-9]+): (.*): unbound variable$'
+      if [[ "$last_error" =~ $regex ]]; then
+        local source line payload
+        source="${BASH_REMATCH[1]}"
+        line="${BASH_REMATCH[2]}"
+        payload="${BASH_REMATCH[3]}"
+        miaou_debug "<unbound_variable source=${source} line=${line} payload=${payload}>"
+        failure_code=$code
+        failure_type='UNBOUND_VARIABLE'
+        failure_payload="${BASH_REMATCH[3]}"
+        error_source=("${BASH_SOURCE[@]}")
+        error_lineno=("${BASH_LINENO[@]}")
+        error_funcname=("${FUNCNAME[@]}")
+        unset 'error_source[0]' 'error_lineno[0]' 'error_funcname[0]'
+        unset 'error_source[-1]' 'error_lineno[-1]' 'error_funcname[-1]'
+        unset 'error_source[-1]' 'error_lineno[-1]' 'error_funcname[-1]'
+        error_source=("$source" "${error_source[@]}")
+        error_lineno=("$line" "${error_lineno[@]}")
+        error_funcname=("${error_funcname[@]}" '<main>')
+      fi
+    fi
+    miaou_debug "</on_exit>"
   fi
 
   if [[ -v failure_type ]]; then