fix return 0 show error_box

bin/miaou-bash

@@ -81,7 +81,6 @@ function on_return {
     print_miaou_error "${BASH_SOURCE[1]}" "${BASH_LINENO[0]}" "${failure_code}" "${failure_type}" "${failure_payload}"
     miaou_debug "<on_return code=$failure_code payload=$failure_payload/>"
   fi
-  true
 }
 
 # overridden function which permits backtracing of the original `exit` statement
@@ -568,7 +567,7 @@ function on_exit {
 
   if ! is_true $CHILD_PROCESS; then
     2>&3 >&3 dump_stderr
-    if [[ -v failure_type ]]; then
+    if [[ -v failure_type && $failure_code -gt 0 ]]; then
       2>&3 >&4 dump_failure
       if [[ -v error_source ]]; then
         2>&3 >&4 dump_stacktrace