fix: taos shell ws take timing with null inputed (#18957)

tools/shell/src/shellWebsocket.c

@@ -37,7 +37,9 @@ static int horizontalPrintWebsocket(WS_RES* wres, double* execute_time) {
   const void* data = NULL;
   int rows;
   ws_fetch_block(wres, &data, &rows);
+  if (wres) {
     *execute_time += (double)(ws_take_timing(wres)/1E6);
+  }
   if (!rows) {
     return 0;
   }
@@ -77,7 +79,9 @@ static int verticalPrintWebsocket(WS_RES* wres, double* pexecute_time) {
   int rows = 0;
   const void* data = NULL;
   ws_fetch_block(wres, &data, &rows);
+  if (wres) {
     *pexecute_time += (double)(ws_take_timing(wres)/1E6);
+  }
   if (!rows) {
     return 0;
   }
@@ -129,7 +133,9 @@ static int dumpWebsocketToFile(const char* fname, WS_RES* wres, double* pexecute
   int rows = 0;
   const void* data = NULL;
   ws_fetch_block(wres, &data, &rows);
+  if (wres) {
     *pexecute_time += (double)(ws_take_timing(wres)/1E6);
+  }
   if (!rows) {
     taosCloseFile(&pFile);
     return 0;
@@ -236,7 +242,10 @@ void shellRunSingleCommandWebsocketImp(char *command) {
     break;
   }
 
-  double execute_time = ws_take_timing(res)/1E6;
+  double execute_time = 0;
+  if (res) {
+    execute_time = ws_take_timing(res)/1E6;
+  }
 
   if (shellRegexMatch(command, "^\\s*use\\s+[a-zA-Z0-9_]+\\s*;\\s*$", REG_EXTENDED | REG_ICASE)) {
     fprintf(stdout, "Database changed.\r\n\r\n");