fix: Handle chunks with empty modules

Closes #22

fixtures/valid-with-empty-modules-in-chunks.json

@@ -0,0 +1,44 @@
+{
+  "errors": [],
+  "warnings": [],
+  "version": "1.15.0",
+  "hash": "9184c60078374c771f6c",
+  "time": 16625,
+  "publicPath": "http://localhost:8000/",
+  "assetsByChunkName": {
+    "commons": ["commons.js", "commons.js.map"]
+  },
+  "assets": [
+    {
+      "name": "commons.js",
+      "size": 3797689,
+      "chunks": [0],
+      "chunkNames": ["commons"],
+      "emitted": true
+    }
+  ],
+  "chunks": [
+    {
+      "id": 0,
+      "rendered": true,
+      "initial": true,
+      "entry": true,
+      "extraAsync": false,
+      "size": 3492266,
+      "names": ["commons"],
+      "files": ["commons.js", "commons.js.map"],
+      "hash": "5088ce796a9301f64f06",
+      "parents": []
+    }
+  ],
+  "modules": [
+    {
+      "id": "module1",
+      "name": "module-name",
+      "size": 500,
+      "reasons": []
+    }
+  ],
+  "filteredModules": 0,
+  "children": []
+}

lib/__tests__/__snapshots__/analyze.js.md

@@ -0,0 +1,33 @@
+# Snapshot report for `lib/__tests__/analyze.js`
+
+The actual snapshot is saved in `analyze.js.snap`.
+
+Generated by [AVA](https://ava.li).
+
+## should handle stats file with a chunk which has empty modules
+
+> Snapshot 1
+
+    {
+      chunks: {
+        0: {
+          id: 0,
+          names: [
+            'commons',
+          ],
+          size: 3492266,
+        },
+      },
+      modules: [
+        {
+          chunks: undefined,
+          deps: 0,
+          depsChains: [],
+          imported: 0,
+          name: 'module-name',
+          reasons: [],
+          size: 500,
+          type: 'file',
+        },
+      ],
+    }

lib/__tests__/analyze.js

@@ -16,3 +16,13 @@ test("should call updateProgressBar correct number of times", t => {
   );
   t.is(calls, 2);
 });
+
+test("should handle stats file with a chunk which has empty modules", t => {
+  t.snapshot(
+    analyze(
+      getStats(f.find("valid-with-empty-modules-in-chunks.json")),
+      [],
+      () => {}
+    )
+  );
+});

lib/analyze.js

@@ -117,7 +117,7 @@ const getModuleType = (name /*?: string */) =>
     : isNodeModules(name) ? "module" : "file";
 
 const flattenChunks = (stats /*: WebpackStats */) /*: Array<WebpackModule> */ =>
-  stats.chunks
+  stats.chunks && stats.chunks[0].modules
     ? stats.chunks.reduce((modules, chunk) => modules.concat(chunk.modules), [])
     : stats.modules;
 
@@ -229,7 +229,7 @@ const joinModules = (modules) /*: { [string]: Module } */ =>
   }, {});
 
 const pickFromModules = (modules) /*: Array<PreModule> */ =>
-  modules.map(module => {
+  modules.filter(Boolean).map(module => {
     const clearName = getModuleName(module.name);
     return {
       clearName,
@@ -268,7 +268,11 @@ const buildModuleDepsChains = (modules, name) => {
   }, []);
 };
 
-const postProcessModules = (modules, ignore, updateProgressBar) => {
+const postProcessModules = (
+  modules /*: { [key: string]: Module }*/,
+  ignore /*: Array<string> */,
+  updateProgressBar /*: Function */
+) => {
   return Object.keys(modules).reduce((acc, name, index) => {
     updateProgressBar(index + 1, "processing", name);
 
@@ -296,13 +300,19 @@ const postProcessModules = (modules, ignore, updateProgressBar) => {
       }
     });
 
-    module.reasons = module.reasons.filter(
-      reason => !mm.isMatch(reason.clearName || reason.moduleName || "", ignore)
-    );
-
-    if (module.reasons.length) {
+    if (!module.reasons) {
       acc[name] = module;
+    } else {
+      module.reasons = module.reasons.filter(
+        reason =>
+          !mm.isMatch(reason.clearName || reason.moduleName || "", ignore)
+      );
+
+      if (module.reasons.length) {
+        acc[name] = module;
+      }
     }
+
     return acc;
   }, {});
 };