Tolerate empty annotation file, throw better error

client/package.json

@@ -100,7 +100,7 @@
     "express": "^4.17.1",
     "fs-extra": "^9.0.1",
     "git-describe": "^4.0.4",
-    "jest": "^26.0.1",
+    "jest": "^26.6.3",
     "jest-transform-stub": "^2.0.0",
     "mime-types": "^2.1.27",
     "mock-fs": "^4.13.0",
@@ -115,7 +115,7 @@
     "rollup-plugin-vue": "^5.1.9",
     "sass": "^1.26.3",
     "sass-loader": "^8.0.2",
-    "ts-jest": "^26.0.0",
+    "ts-jest": "^26.5.2",
     "tsc-alias": "^1.2.0",
     "typescript": "~3.8.3",
     "vue-cli-plugin-electron-builder": "^2.0.0-beta.5",

client/platform/desktop/backend/native/common.spec.ts

@@ -126,6 +126,10 @@ mockfs({
       'otherfile.txt': '',
       nomime: '',
     },
+    annotationEmptySuccess: {
+      'video1.mp4': '',
+      'result_foo.json': '',
+    },
     annotationFail: {
       'video1.mp4': '',
       'file1.csv': '',
@@ -319,6 +323,12 @@ describe('native.common', () => {
     expect(meta.originalBasePath).toBe('/home/user/data/videoSuccess');
   });
 
+  it('importMedia empty json file success', async () => {
+    const meta = await common.importMedia(settings, '/home/user/data/annotationEmptySuccess/video1.mp4', updater, { checkMedia, convertMedia });
+    const tracks = await common.loadDetections(settings, meta.id);
+    expect(tracks).toEqual({});
+  });
+
   it('importMedia various failure modes', async () => {
     await expect(common.importMedia(settings, '/fake/path', updater, { checkMedia, convertMedia }))
       .rejects.toThrow('file or directory not found');

client/platform/desktop/backend/native/common.ts

@@ -109,7 +109,12 @@ async function getValidatedProjectDir(settings: Settings, datasetId: string) {
  */
 async function loadJsonMetadata(metaAbsPath: string): Promise<JsonMeta> {
   const rawBuffer = await fs.readFile(metaAbsPath, 'utf-8');
-  const metaJson = JSON.parse(rawBuffer);
+  let metaJson;
+  try {
+    metaJson = JSON.parse(rawBuffer);
+  } catch (err) {
+    throw new Error(`Unable to parse ${metaAbsPath}: ${err}`);
+  }
   /* check if this file meets the current schema version */
   if ('version' in metaJson) {
     const { version } = metaJson;
@@ -127,7 +132,15 @@ async function loadJsonMetadata(metaAbsPath: string): Promise<JsonMeta> {
  */
 async function loadJsonTracks(tracksAbsPath: string): Promise<MultiTrackRecord> {
   const rawBuffer = await fs.readFile(tracksAbsPath, 'utf-8');
-  const annotationData = JSON.parse(rawBuffer) as MultiTrackRecord;
+  if (rawBuffer.length === 0) {
+    return {}; // Return empty object if file was empty
+  }
+  let annotationData: MultiTrackRecord = {};
+  try {
+    annotationData = JSON.parse(rawBuffer) as MultiTrackRecord;
+  } catch (err) {
+    throw new Error(`Unable to parse ${tracksAbsPath}: ${err}`);
+  }
   // TODO: somehow verify the schema of this file
   if (Array.isArray(annotationData)) {
     throw new Error('object expected in track json');