fix(eval): fix crash with :breakadd expr when calling user func

src/nvim/eval/userfunc.c

@@ -3906,41 +3906,57 @@ funccall_T *get_funccal(void)
   return funccal;
 }
 
+/// @return  dict used for local variables in the current funccal or
+///          NULL if there is no current funccal.
+dict_T *get_funccal_local_dict(void)
+{
+  if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0) {
+    return NULL;
+  }
+  return &get_funccal()->fc_l_vars;
+}
+
 /// @return  hashtable used for local variables in the current funccal or
 ///          NULL if there is no current funccal.
 hashtab_T *get_funccal_local_ht(void)
 {
-  if (current_funccal == NULL) {
+  dict_T *d = get_funccal_local_dict();
-    return NULL;
+  return d != NULL ? &d->dv_hashtab : NULL;
-  }
-  return &get_funccal()->fc_l_vars.dv_hashtab;
 }
 
 /// @return   the l: scope variable or
 ///           NULL if there is no current funccal.
 dictitem_T *get_funccal_local_var(void)
 {
-  if (current_funccal == NULL) {
+  if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0) {
     return NULL;
   }
   return (dictitem_T *)&get_funccal()->fc_l_vars_var;
 }
 
+/// @return  the dict used for argument in the current funccal or
+///          NULL if there is no current funccal.
+dict_T *get_funccal_args_dict(void)
+{
+  if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0) {
+    return NULL;
+  }
+  return &get_funccal()->fc_l_avars;
+}
+
 /// @return  the hashtable used for argument in the current funccal or
 ///          NULL if there is no current funccal.
 hashtab_T *get_funccal_args_ht(void)
 {
-  if (current_funccal == NULL) {
+  dict_T *d = get_funccal_args_dict();
-    return NULL;
+  return d != NULL ? &d->dv_hashtab : NULL;
-  }
-  return &get_funccal()->fc_l_avars.dv_hashtab;
 }
 
 /// @return  the a: scope variable or
 ///          NULL if there is no current funccal.
 dictitem_T *get_funccal_args_var(void)
 {
-  if (current_funccal == NULL) {
+  if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0) {
     return NULL;
   }
   return (dictitem_T *)&get_funccal()->fc_l_avars_var;
@@ -3949,7 +3965,7 @@ dictitem_T *get_funccal_args_var(void)
 /// List function variables, if there is a function.
 void list_func_vars(int *first)
 {
-  if (current_funccal != NULL) {
+  if (current_funccal != NULL && current_funccal->fc_l_vars.dv_refcount > 0) {
     list_hashtable_vars(&current_funccal->fc_l_vars.dv_hashtab, "l:", false,
                         first);
   }

src/nvim/eval/vars.c

@@ -2483,7 +2483,6 @@ dictitem_T *find_var_in_ht(hashtab_T *const ht, int htname, const char *const va
 static hashtab_T *find_var_ht_dict(const char *name, const size_t name_len, const char **varname,
                                    dict_T **d)
 {
-  funccall_T *funccal = get_funccal();
   *d = NULL;
 
   if (name_len == 0) {
@@ -2503,11 +2502,12 @@ static hashtab_T *find_var_ht_dict(const char *name, const size_t name_len, cons
       return &compat_hashtab;
     }
 
-    if (funccal == NULL) {  // global variable
+    *d = get_funccal_local_dict();
-      *d = get_globvar_dict();
+    if (*d != NULL) {  // local variable
-    } else {  // l: variable
+      goto end;
-      *d = &funccal->fc_l_vars;
     }
+
+    *d = get_globvar_dict();  // global variable
     goto end;
   }
 
@@ -2529,10 +2529,10 @@ static hashtab_T *find_var_ht_dict(const char *name, const size_t name_len, cons
     *d = curtab->tp_vars;
   } else if (*name == 'v') {  // v: variable
     *d = get_vimvar_dict();
-  } else if (*name == 'a' && funccal != NULL) {  // function argument
+  } else if (*name == 'a') {  // a: function argument
-    *d = &funccal->fc_l_avars;
+    *d = get_funccal_args_dict();
-  } else if (*name == 'l' && funccal != NULL) {  // local variable
+  } else if (*name == 'l') {  // l: local variable
-    *d = &funccal->fc_l_vars;
+    *d = get_funccal_local_dict();
   } else if (*name == 's'  // script variable
              && (current_sctx.sc_sid > 0 || current_sctx.sc_sid == SID_STR
                  || current_sctx.sc_sid == SID_LUA)