add check for author && author.login to avoid errors when author is null

lib/dco.js

@@ -14,8 +14,10 @@ module.exports = async function (commits, isRequiredFor) {
 
   for (const {commit, author, parents} of commits) {
     const isMerge = parents && parents.length > 1
-    const signoffRequired = await isRequiredFor(author.login)
-    if (isMerge || author.type === 'Bot' || (!signoffRequired && commit.verification.verified)) {
+    const signoffRequired = !author || await isRequiredFor(author.login)
+    if (isMerge || (!signoffRequired && commit.verification.verified)) {
+      continue
+    } else if (!author || author.type === 'Bot') {
       continue
     }
     const match = regex.exec(commit.message)

package.json

@@ -16,7 +16,7 @@
   "devDependencies": {
     "eslint-plugin-import": "^2.11.0",
     "jest": "^22.4.3",
-    "nock": "^9.2.5",
+    "nock": "^9.2.6",
     "smee-client": "^1.0.1",
     "standard": "^11.0.0"
   },

test/dco.test.js

@@ -406,4 +406,25 @@ describe('dco', () => {
       expect(JSON.stringify(dcoObject)).toBe(success)
     }
   )
+
+  test(
+    'returns success if author does not exist but everything else is ok',
+    async () => {
+      const commit = {
+        message: 'What a nice day!\n\nSigned-off-by: Bex Warner <bexmwarner@gmail.com>',
+        author: {
+          name: 'Bexo',
+          email: 'bexo@gmail.com'
+        },
+        committer: {
+          name: 'Bex Warner',
+          email: 'bexmwarner@gmail.com'
+        }
+      }
+      const author = null
+      const dcoObject = await getDCOStatus([{commit, author, parents: []}], alwaysRequireSignoff)
+
+      expect(JSON.stringify(dcoObject)).toBe(success)
+    }
+  )
 })