fix: coverity issues

CID: 399890

source/libs/scalar/src/filter.c

@@ -1135,7 +1135,12 @@ int32_t filterAddUnit(SFilterInfo *info, uint8_t optr, SFilterFieldId *left, SFi
 int32_t filterAddUnitToGroup(SFilterGroup *group, uint32_t unitIdx) {
   if (group->unitNum >= group->unitSize) {
     group->unitSize += FILTER_DEFAULT_UNIT_SIZE;
-    group->unitIdxs = taosMemoryRealloc(group->unitIdxs, group->unitSize * sizeof(*group->unitIdxs));
+
+    void *tmp = taosMemoryRealloc(group->unitIdxs, group->unitSize * sizeof(*group->unitIdxs));
+    if (tmp == NULL) {
+      return TSDB_CODE_OUT_OF_MEMORY;
+    }
+    group->unitIdxs = tmp;
   }
 
   group->unitIdxs[group->unitNum++] = unitIdx;