Require consistent return values.

This enables the eslint rule that requires all functions to consistently
either return a value or not return a value.

Change-Id: I98b579f3689c3b6c74968116824231bb792bd9dd

Author: TheModMaker

.eslintrc.js

@@ -39,9 +39,9 @@ module.exports = {
         // Things we should probably fix, but in stages in multiple commits: {{{
 
         // These could catch real bugs
-        "consistent-return": "off",
         "default-case": "off",
-        "no-extra-bind": "off",
+        // TODO: Enable no-loop-func in next eslint release.  We can't use it
+        // now since it doesn't allow capturing "const" variables, which is safe
         "no-loop-func": "off",
         "no-unused-expressions": "off",  // Conflicts with some Closure declarations
         "prefer-promise-reject-errors": "off",
@@ -82,6 +82,7 @@ module.exports = {
         // "Best practices" rules we should be able to pass, but are not part of "eslint:recommended": {{{
         "accessor-pairs": "error",
         "array-callback-return": "error",
+        "consistent-return": "error",
         "no-alert": "error",
         "no-caller": "error",
         "no-catch-shadow": "error",

demo/main.js

@@ -733,6 +733,7 @@ class ShakaDemoMain {
         return objOn[split[0]];
       }
     }
+    return undefined;
   }
 
   /**

lib/cast/cast_proxy.js

@@ -199,7 +199,7 @@ shaka.cast.CastProxy.prototype.cast = function() {
   return this.sender_.cast(initState).then(() => {
     if (!this.localPlayer_) {
       // We've already been destroyed.
-      return;
+      return null;
     }
 
     // Unload the local manifest when casting succeeds.

lib/dash/dash_parser.js

@@ -417,7 +417,7 @@ shaka.dash.DashParser.prototype.requestManifest_ = function() {
   return operation.promise.then((response) => {
     // Detect calls to stop().
     if (!this.playerInterface_) {
-      return;
+      return null;
     }
 
     // For redirections add the response uri to the first entry in the

lib/hls/hls_parser.js

@@ -279,7 +279,7 @@ shaka.hls.HlsParser.prototype.stop = function() {
  */
 shaka.hls.HlsParser.prototype.update = function() {
   if (!this.isLive_()) {
-    return;
+    return Promise.resolve();
   }
 
   /** @type {!Array.<!Promise>} */

lib/hls/manifest_text_parser.js

@@ -153,7 +153,6 @@ shaka.hls.ManifestTextParser.prototype.parseSegments_ =
       }
     } else if (shaka.hls.Utils.isComment(line)) {
       // Skip comments.
-      return [];
     } else {
       const verbatimSegmentUri = line.trim();
       const absoluteSegmentUri = shaka.hls.Utils.constructAbsoluteUri(

lib/media/drm_engine.js

@@ -491,7 +491,7 @@ shaka.media.DrmEngine.prototype.attach = function(video) {
   const setServerCertificate = this.setServerCertificate();
 
   return Promise.all([setMediaKeys, setServerCertificate]).then(() => {
-    if (this.isDestroying_) { return Promise.reject(); }
+    if (this.isDestroying_) { return; }
 
     this.createOrLoad();
     if (!this.currentDrmInfo_.initData.length &&
@@ -504,7 +504,7 @@ shaka.media.DrmEngine.prototype.attach = function(video) {
     }
   }).catch((error) => {
     if (this.isDestroying_) { return; }
-    return Promise.reject(error);
+    throw error;
   });
 };
 
@@ -530,11 +530,11 @@ shaka.media.DrmEngine.prototype.setServerCertificate = async function() {
                           ' system.  The server certificate has been ignored.');
       }
     } catch (exception) {
-      return Promise.reject(new shaka.util.Error(
+      throw new shaka.util.Error(
         shaka.util.Error.Severity.CRITICAL,
         shaka.util.Error.Category.DRM,
         shaka.util.Error.Code.INVALID_SERVER_CERTIFICATE,
-        exception.message));
+        exception.message);
     }
   }
 };
@@ -873,21 +873,21 @@ shaka.media.DrmEngine.prototype.queryMediaKeys_ = function(configsByKeySystem) {
       if (hasLicenseServer != shouldHaveLicenseServer) return;
 
       p = p.catch(() => {
-        if (this.isDestroying_) { return; }
+        if (this.isDestroying_) { return null; }
         return navigator.requestMediaKeySystemAccess(keySystem, [config]);
       });
     });
   });
 
   p = p.catch(() => {
-    return Promise.reject(new shaka.util.Error(
+    throw new shaka.util.Error(
         shaka.util.Error.Severity.CRITICAL,
         shaka.util.Error.Category.DRM,
-        shaka.util.Error.Code.REQUESTED_KEY_SYSTEM_CONFIG_UNAVAILABLE));
+        shaka.util.Error.Code.REQUESTED_KEY_SYSTEM_CONFIG_UNAVAILABLE);
   });
 
   p = p.then((mediaKeySystemAccess) => {
-    if (this.isDestroying_) { return Promise.reject(); }
+    if (this.isDestroying_) { return null; }
 
     // Get the set of supported content types from the audio and video
     // capabilities. Avoid duplicates so that it is easier to read what is
@@ -915,16 +915,16 @@ shaka.media.DrmEngine.prototype.queryMediaKeys_ = function(configsByKeySystem) {
         configsByKeySystem.get(mediaKeySystemAccess.keySystem));
 
     if (!this.currentDrmInfo_.licenseServerUri) {
-      return Promise.reject(new shaka.util.Error(
+      throw new shaka.util.Error(
           shaka.util.Error.Severity.CRITICAL,
           shaka.util.Error.Category.DRM,
           shaka.util.Error.Code.NO_LICENSE_SERVER_GIVEN,
-          this.currentDrmInfo_.keySystem));
+          this.currentDrmInfo_.keySystem);
     }
 
     return mediaKeySystemAccess.createMediaKeys();
   }).then((mediaKeys) => {
-    if (this.isDestroying_) { return Promise.reject(); }
+    if (this.isDestroying_) { return; }
     shaka.log.info('Created MediaKeys object for key system',
                    this.currentDrmInfo_.keySystem);
 
@@ -937,15 +937,15 @@ shaka.media.DrmEngine.prototype.queryMediaKeys_ = function(configsByKeySystem) {
     this.currentDrmInfo_ = null;
     this.supportedTypes_.clear();
     if (exception instanceof shaka.util.Error) {
-      return Promise.reject(exception);
+      throw exception;
     }
 
     // We failed to create MediaKeys.  This generally shouldn't happen.
-    return Promise.reject(new shaka.util.Error(
+    throw new shaka.util.Error(
         shaka.util.Error.Severity.CRITICAL,
         shaka.util.Error.Category.DRM,
         shaka.util.Error.Code.FAILED_TO_CREATE_CDM,
-        exception.message));
+        exception.message);
   });
 
   instigator.reject();
@@ -1041,7 +1041,7 @@ shaka.media.DrmEngine.prototype.loadOfflineSession_ = function(sessionId) {
   this.activeSessions_.set(session, metadata);
 
   return session.load(sessionId).then((present) => {
-    if (this.isDestroying_) { return Promise.reject(); }
+    if (this.isDestroying_) { return null; }
     shaka.log.v2('Loaded offline session', sessionId, present);
 
     if (!present) {
@@ -1051,7 +1051,7 @@ shaka.media.DrmEngine.prototype.loadOfflineSession_ = function(sessionId) {
           shaka.util.Error.Severity.CRITICAL,
           shaka.util.Error.Category.DRM,
           shaka.util.Error.Code.OFFLINE_SESSION_REMOVED));
-      return;
+      return null;
     }
 
     // TODO: We should get a key status change event.  Remove once Chrome CDM

lib/media/streaming_engine.js

@@ -434,7 +434,7 @@ shaka.media.StreamingEngine.prototype.start = async function() {
       this.manifest_.periods[needPeriodIndex]);
   if (!initialStreams.variant && !initialStreams.text) {
     shaka.log.error('init: no Streams chosen');
-    return new shaka.util.Error(
+    throw new shaka.util.Error(
         shaka.util.Error.Severity.CRITICAL,
         shaka.util.Error.Category.STREAMING,
         shaka.util.Error.Code.INVALID_STREAMS_CHOSEN);
@@ -1082,7 +1082,7 @@ shaka.media.StreamingEngine.prototype.setupPeriod_ = function(periodIndex) {
 
   // Serialize Period set up.
   this.setupPeriodPromise_ = this.setupPeriodPromise_.then(() => {
-    if (this.destroyed_) return;
+    if (this.destroyed_) return null;
     return this.setupStreams_(streams);
   }).then(() => {
     if (this.destroyed_) return;
@@ -1644,7 +1644,7 @@ shaka.media.StreamingEngine.prototype.fetchAndAppend_ = function(
 
 
   Promise.all([initSourceBuffer, fetchSegment]).then((results) => {
-    if (this.destroyed_ || this.fatalError_) return;
+    if (this.destroyed_ || this.fatalError_) return null;
     return this.append_(mediaState,
                         presentationTime,
                         currentPeriod,
@@ -1848,7 +1848,7 @@ shaka.media.StreamingEngine.prototype.initSourceBuffer_ = function(
   const fetchInit =
       this.fetch_(mediaState, mediaState.stream.initSegmentReference);
   const appendInit = fetchInit.then((initSegment) => {
-    if (this.destroyed_) return;
+    if (this.destroyed_) return null;
     shaka.log.v1(logPrefix, 'appending init segment');
     const hasClosedCaptions = mediaState.stream.closedCaptions &&
         mediaState.stream.closedCaptions.size > 0;
@@ -1892,7 +1892,7 @@ shaka.media.StreamingEngine.prototype.append_ = function(
   }
 
   return this.evict_(mediaState, presentationTime).then(() => {
-    if (this.destroyed_) return;
+    if (this.destroyed_) return null;
     shaka.log.v1(logPrefix, 'appending media segment');
 
     // MediaSourceEngine expects times relative to the start of the
@@ -1909,8 +1909,6 @@ shaka.media.StreamingEngine.prototype.append_ = function(
     // We must use |stream| because switch() may have been called.
     mediaState.lastStream = stream;
     mediaState.lastSegmentReference = reference;
-
-    return Promise.resolve();
   });
 };
 
@@ -2410,6 +2408,8 @@ shaka.media.StreamingEngine.prototype.clearBuffer_ =
           if (!this.destroyed_ && flush) {
             return this.playerInterface_.mediaSourceEngine.flush(
                 mediaState.type);
+          } else {
+            return null;
           }
         });
   }

lib/net/backoff.js

@@ -105,7 +105,10 @@ shaka.net.Backoff.prototype.attempt = async function() {
     if (this.autoReset_) {
       this.reset_();
     } else {
-      return Promise.reject();
+      throw new shaka.util.Error(
+          shaka.util.Error.Severity.CRITICAL,
+          shaka.util.Error.Category.PLAYER,
+          shaka.util.Error.Code.ATTEMPTS_EXHAUSTED);
     }
   }
 

lib/net/networking_engine.js

@@ -525,16 +525,19 @@ shaka.net.NetworkingEngine.prototype.send_ = function(
 
     return responseAndGotProgress;
   }, (error) => {
-    if (error && error.code == shaka.util.Error.Code.OPERATION_ABORTED) {
-      // Don't change anything if the operation was aborted.
-      throw error;
-    }
-
     if (this.destroyed_) {
       return shaka.util.AbortableOperation.aborted();
     }
 
-    if (error && error.severity == shaka.util.Error.Severity.RECOVERABLE) {
+    if (error.code == shaka.util.Error.Code.OPERATION_ABORTED) {
+      // Don't change anything if the operation was aborted.
+      throw error;
+    } else if (error.code == shaka.util.Error.Code.ATTEMPTS_EXHAUSTED) {
+      goog.asserts.assert(lastError, 'Should have last error');
+      throw lastError;
+    }
+
+    if (error.severity == shaka.util.Error.Severity.RECOVERABLE) {
       // Don't pass in a non-shaka error, even if one is somehow thrown;
       // instead, call the listener with a null error.
       const errorOrNull = error instanceof shaka.util.Error ? error : null;
@@ -548,8 +551,7 @@ shaka.net.NetworkingEngine.prototype.send_ = function(
     }
 
     // The error was not recoverable, so do not try again.
-    // Rethrow the error so the Promise chain stays rejected.
-    throw error || lastError;
+    throw error;
   });
 
   return sendOperation;