core, ethdb: two tiny fixes (#17183)

* ethdb: fix memory database

* core: fix bloombits checking

* core: minor polish

ethdb/memory_database.go

@@ -96,7 +96,10 @@ func (db *MemDatabase) NewBatch() Batch {
 
 func (db *MemDatabase) Len() int { return len(db.db) }
 
-type kv struct{ k, v []byte }
+type kv struct {
+	k, v []byte
+	del  bool
+}
 
 type memBatch struct {
 	db     *MemDatabase
@@ -105,13 +108,14 @@ type memBatch struct {
 }
 
 func (b *memBatch) Put(key, value []byte) error {
-	b.writes = append(b.writes, kv{common.CopyBytes(key), common.CopyBytes(value)})
+	b.writes = append(b.writes, kv{common.CopyBytes(key), common.CopyBytes(value), false})
 	b.size += len(value)
 	return nil
 }
 
 func (b *memBatch) Delete(key []byte) error {
-	b.writes = append(b.writes, kv{common.CopyBytes(key), nil})
+	b.writes = append(b.writes, kv{common.CopyBytes(key), nil, true})
+	b.size += 1
 	return nil
 }
 
@@ -120,7 +124,7 @@ func (b *memBatch) Write() error {
 	defer b.db.lock.Unlock()
 
 	for _, kv := range b.writes {
-		if kv.v == nil {
+		if kv.del {
 			delete(b.db.db, string(kv.k))
 			continue
 		}