patch 8.2.1251: Vim9: warning for pointer usage, test failure undetected

Problem:    Vim9: warning for pointer usage, test failure undetected.
Solution:   Fix pointer indirection.  Give error when executing function
            failed for any reason.  Fix instruction names.

src/userfunc.c

@@ -2122,7 +2122,7 @@ theend:
     return ret;
 }
 
-    static char_u *
+    char_u *
 printable_func_name(ufunc_T *fp)
 {
     return fp->uf_name_exp != NULL ? fp->uf_name_exp : fp->uf_name;