Update utslmemo.tsf

编辑器错误判断

funcext/tvclib/utslmemo.tsf

@@ -1202,7 +1202,11 @@ type TCustomMemo = class(TCustomScrollControl,TCustomMemoCmd) //
         if fUndoList.CanUndo then
         begin
             lk := new tcountlocker(ftmemlockv);
+            try 
             UndoItem();
+            except
+                ClearUndo();  
+            end 
         end
     end
     function Redo();
@@ -1210,7 +1214,11 @@ type TCustomMemo = class(TCustomScrollControl,TCustomMemoCmd) //
         if fRedoList.CanUndo then 
         begin
             lk := new tcountlocker(ftmemlockv);
-            RedoItem();
+            try 
+                RedoItem();
+            except
+                ClearUndo();  
+            end 
         end 
     end
     function CharInput(c);virtual;//插入字符
@@ -2365,11 +2373,7 @@ type TCustomMemo = class(TCustomScrollControl,TCustomMemoCmd) //
                 if not s then return "";
                 bg := min(bb[1],ee[1]);
                 ed := max(bb[1],ee[1]);
-                try 
                 if bg<ed then return s[bg:(ed-1)]; //2023078 出错
-                except
-                
-                end
                 return "";
                 {if ee[1]>bb[1]and ee[1]>1 then 
                 try