In EXT:SAFE-EVAL avoid the debugger being entered at all.

src/CHANGELOG

@@ -14,6 +14,9 @@ ECL 10.3.2:
  - The reimplementation of DIRECTORY introduced a bug in pathnames with ending
    double wildcars, such as "/foo/**/".
 
+ - EXT:SAFE-EVAL (or cl_safe_eval in C) would attempt to start the debugger
+   when an error was signaled.
+
 * Visible changes:
 
  - The source location annotator records the original pathnames, not the

src/lsp/top.lsp

@@ -1480,13 +1480,13 @@ supplied, then SAFE-EVAL will not use a debugger but rather return that
 value."
   (let ((output nil) (ok nil))
     (unwind-protect
-         (if err-value-p
-             (let ((*break-enable* nil))
-               (setf output (si::eval-with-env form env)
-                     ok t))
-             (handler-bind ((serious-condition #'invoke-debugger))
-               (setf output (si::eval-with-env form env)
-                     ok t)))
+         (handler-bind ((serious-condition
+                         (if err-value-p
+                             #'(lambda (c)
+                                 (return-from safe-eval err-value))
+                             #'invoke-debugger)))
+           (setf output (si::eval-with-env form env)
+                 ok t))
       (return-from safe-eval (if ok output err-value)))))
 
 #-ecl-min