Hotfix/sangshuduo/td 3197 taosdemo coverity scan for master (#7013)

* [TD-3197]<fix>: taosdemo and taosdump coverity scan issues.

* exit if read sample file failed.

* fix converity scan issue.

* fix coverity scan issue.

* fix coverity scan memory leak.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

src/kit/taosdemo/taosdemo.c

@@ -5920,14 +5920,15 @@ static int32_t prepareStbStmt(
 
         if (-1 == prepareStbStmtBind(
                     tagsArray, stbInfo, tagRand, -1, -1, false /* is tag */)) {
-            free(tagsArray);
+            tmfree(tagsValBuf);
+            tmfree(tagsArray);
             return -1;
         }
 
         ret = taos_stmt_set_tbname_tags(stmt, tableName, (TAOS_BIND *)tagsArray);
 
         tmfree(tagsValBuf);
-        tmfree((char *)tagsArray);
+        tmfree(tagsArray);
     } else {
         ret = taos_stmt_set_tbname(stmt, tableName);
     }