Add a small bit of error handling, copied from hb-subset

index.js

@@ -66,8 +66,18 @@ async function subsetFont(
   const result = exports.hb_face_reference_blob(subset);
 
   const offset = exports.hb_blob_get_data(result, 0);
+  const subsetByteLength = exports.hb_blob_get_length(result);
+  if (subsetByteLength === 0) {
+    exports.hb_blob_destroy(result);
+    exports.hb_face_destroy(subset);
+    exports.free(fontBuffer);
+    throw new Error(
+      'Failed to create subset font, maybe the input file is corrupted?'
+    );
+  }
+
   const subsetFont = Buffer.from(
-    heapu8.subarray(offset, offset + exports.hb_blob_get_length(result))
+    heapu8.subarray(offset, offset + subsetByteLength)
   );
 
   // Clean up

test/index.js

@@ -199,4 +199,22 @@ describe('subset-font', function () {
       expect(result.slice(0, 4).toString(), 'to equal', 'wOF2');
     });
   });
+
+  describe('with a truncated font', function () {
+    before(async function () {
+      this.truncatedTtfFont = await readFile(
+        pathModule.resolve(__dirname, '..', 'testdata', 'FZZJ-ZSXKJW.ttf')
+      );
+    });
+
+    it('should error out', async function () {
+      await expect(
+        subsetFont(this.truncatedTtfFont, 'abcd', {
+          targetFormat: 'woff',
+        }),
+        'to be rejected with',
+        'Failed to create subset font, maybe the input file is corrupted?'
+      );
+    });
+  });
 });