fix: handle invalid travis supportPolicy

lib/manager/travis/package.js

@@ -21,13 +21,19 @@ async function getPackageUpdates(config) {
   if (!(supportPolicy && supportPolicy.length)) {
     supportPolicy = ['lts'];
   }
+  for (const policy of supportPolicy) {
+    if (!Object.keys(policies).includes(policy)) {
+      logger.warn(`Unknown supportPolicy: ${policy}`);
+      return [];
+    }
+  }
+  logger.debug({ supportPolicy }, `supportPolicy`);
   let newVersion = supportPolicy
     .map(policy => policies[policy])
     .reduce((result, policy) => result.concat(policy), [])
     .sort() // sort combined array
     .reverse() // we want to order latest to oldest
     .map(version => `${version}`); // convert to strings
-  logger.debug({ newVersion });
   if (config.pinVersions || semver.valid(config.currentVersion[0])) {
     const releases = await getRepoReleases('nodejs/node');
     newVersion = newVersion.map(version =>

test/manager/travis/package.spec.js

@@ -12,6 +12,11 @@ describe('lib/workers/package/node', () => {
         ...defaultConfig,
       };
     });
+    it('returns empty if invalid supportPolicy', async () => {
+      config.currentVersion = ['6', '8'];
+      config.supportPolicy = ['foo'];
+      expect(await node.getPackageUpdates(config)).toEqual([]);
+    });
     it('returns empty if matching', async () => {
       config.currentVersion = ['6', '8'];
       config.supportPolicy = ['lts_active'];