Fix bug in IPC stream decoding when an empty batch is part of the stream

Author: roelentless

src/decode/message.js

@@ -75,6 +75,10 @@ export function decodeMessage(buf, index) {
       }
       // @ts-ignore
       content.body = body;
+    } else if (type !== MessageHeader.Schema) {
+      // table-from-ipc.js buffer accessor requires body to exist, even for empty batches
+      // @ts-ignore
+      content.body = new Uint8Array(0);
     }
   }
 

test/data/file-with-3-batches.bin

@@ -0,0 +1,14 @@
+import { readFileSync } from 'node:fs';
+import { tableFromIPC } from '../src/index.js';
+import assert from 'node:assert';
+
+describe('Empty batch handling', () => {
+  it('should decode IPC stream with empty RecordBatch', () => {
+    const data = readFileSync('test/data/file-with-3-batches.bin');
+    const table = tableFromIPC(data);
+    
+    assert.strictEqual(table.numRows, 5, 'Expected 5 total rows (3 + 0 + 2)');
+    assert.strictEqual(table.numCols, 2, 'Expected 2 columns');
+  });
+});
+