Merge pull request #17574 from taosdata/fix/TD-19741

fix: return 0 usage when pTsdb is null

source/dnode/vnode/src/tsdb/tsdbCache.c

@@ -1492,4 +1492,11 @@ void tsdbCacheSetCapacity(SVnode *pVnode, size_t capacity) {
 
 size_t tsdbCacheGetCapacity(SVnode *pVnode) { return taosLRUCacheGetCapacity(pVnode->pTsdb->lruCache); }
 
-size_t tsdbCacheGetUsage(SVnode *pVnode) { return taosLRUCacheGetUsage(pVnode->pTsdb->lruCache); }
+size_t tsdbCacheGetUsage(SVnode *pVnode) {
+  size_t usage = 0;
+  if (pVnode->pTsdb != NULL) {
+    usage = taosLRUCacheGetUsage(pVnode->pTsdb->lruCache);
+  }
+
+  return usage;
+}