Hotfix/sangshuduo/td 3197 taosdemo coverity scan for master (#6906)

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

* exit if read sample file failed.

* fix converity scan issue.

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

src/kit/taosdemo/taosdemo.c

@@ -5003,6 +5003,7 @@ static int64_t generateData(char *recBuf, char **data_type,
             if (s == NULL) {
                 errorPrint("%s() LN%d, memory allocation %d bytes failed\n",
                         __func__, __LINE__, lenOfBinary + 1);
+                exit(-1);
             }
             rand_string(s, lenOfBinary);
             pstr += sprintf(pstr, ",\"%s\"", s);
@@ -5012,6 +5013,7 @@ static int64_t generateData(char *recBuf, char **data_type,
             if (s == NULL) {
                 errorPrint("%s() LN%d, memory allocation %d bytes failed\n",
                         __func__, __LINE__, lenOfBinary + 1);
+                exit(-1);
             }
             rand_string(s, lenOfBinary);
             pstr += sprintf(pstr, ",\"%s\"", s);
@@ -6748,7 +6750,9 @@ static void startMultiThreadInsertData(int threads, char* db_name,
                 char buffer[3000];
                 char *pstr = buffer;
 
-                if (AUTO_CREATE_SUBTBL == superTblInfo->autoCreateTable) {
+                if ((superTblInfo)
+                        && (AUTO_CREATE_SUBTBL
+                            == superTblInfo->autoCreateTable)) {
                     pstr += sprintf(pstr, "INSERT INTO ? USING %s TAGS(?",
                             superTblInfo->sTblName);
                     for (int tag = 0; tag < (superTblInfo->tagCount - 1); tag ++ ) {