fix(driver):csharp example ci failed for read from null point

docs/examples/csharp/wsConnect/Program.cs

@@ -9,9 +9,10 @@ namespace Examples
         {
             string DSN = "ws://root:taosdata@127.0.0.1:6041/test";
             IntPtr wsConn = LibTaosWS.WSConnectWithDSN(DSN);
+  
             if (wsConn == IntPtr.Zero)
             {
-                throw new Exception($"get WS connection failed,reason:{LibTaosWS.WSErrorStr(IntPtr.Zero)} code:{LibTaosWS.WSErrorNo(IntPtr.Zero)}");
+                throw new Exception("get WS connection failed");
             }
             else
             {

docs/examples/csharp/wsInsert/Program.cs

@@ -13,7 +13,7 @@ namespace Examples
             // Assert if connection is validate
             if (wsConn == IntPtr.Zero)
             {
-                throw new Exception($"get WS connection failed,reason:{LibTaosWS.WSErrorStr(IntPtr.Zero)} code:{LibTaosWS.WSErrorNo(IntPtr.Zero)}");
+                throw new Exception("get WS connection failed");
             }
             else
             {

docs/examples/csharp/wsQuery/Program.cs

@@ -13,7 +13,7 @@ namespace Examples
             IntPtr wsConn = LibTaosWS.WSConnectWithDSN(DSN);
             if (wsConn == IntPtr.Zero)
             {
-                throw new Exception($"get WS connection failed,reason:{LibTaosWS.WSErrorStr(IntPtr.Zero)} code:{LibTaosWS.WSErrorNo(IntPtr.Zero)}");
+                throw new Exception("get WS connection failed");
             }
             else
             {

docs/examples/csharp/wsStmt/Program.cs

@@ -21,7 +21,7 @@ namespace Examples
             IntPtr wsConn = LibTaosWS.WSConnectWithDSN(DSN);
             if (wsConn == IntPtr.Zero)
             {
-                throw new Exception($"get WS connection failed,reason:{LibTaosWS.WSErrorStr(IntPtr.Zero)} code:{LibTaosWS.WSErrorNo(IntPtr.Zero)}");
+                throw new Exception($"get WS connection failed");
             }
             else
             {