fix flush

Author: mafintosh

index.js

@@ -58,7 +58,7 @@ class HyperBlobsBatch {
   }
 
   async flush () {
-    await this.core.append(this.blocks)
+    await this.blobs.core.append(this.blocks)
     this.blocks = []
     this.bytes = 0
   }

test/all.js

@@ -392,6 +392,8 @@ test('basic batch', async (t) => {
     const buf = await batch.get(id)
     t.alike(buf, Buffer.from('hej verden'))
   }
+
+  await batch.flush()
 })
 
 async function createPair () {