fix(icon): Log network errors without throwing exceptions.

fixes #2530

closes #3718

src/components/icon/iconService.js

@@ -394,10 +394,8 @@
      if ( urlRegex.test(id)     ) return loadByURL(id).then( cacheIcon(id) );
      if ( id.indexOf(':') == -1 ) id = '$default:' + id;
 
-     return loadByID(id)
-         .catch(loadFromIconSet)
-         .catch(announceIdNotFound)
-         .catch(announceNotFound)
+     var load = config[id] ? loadByID : loadFromIconSet;
+     return load(id)
          .then( cacheIcon(id) );
    }
 
@@ -435,9 +433,8 @@
     *
     */
    function loadByID(id) {
-     var iconConfig = config[id];
-
-     return !iconConfig ? $q.reject(id) : loadByURL(iconConfig.url).then(function(icon) {
+    var iconConfig = config[id];
+     return loadByURL(iconConfig.url).then(function(icon) {
        return new Icon(icon, iconConfig);
      });
    }
@@ -450,12 +447,19 @@
      var setName = id.substring(0, id.lastIndexOf(':')) || '$default';
      var iconSetConfig = config[setName];
 
-     return !iconSetConfig ? $q.reject(id) : loadByURL(iconSetConfig.url).then(extractFromSet);
+     return !iconSetConfig ? announceIdNotFound(id) : loadByURL(iconSetConfig.url).then(extractFromSet);
 
      function extractFromSet(set) {
        var iconName = id.slice(id.lastIndexOf(':') + 1);
        var icon = set.querySelector('#' + iconName);
-       return !icon ? $q.reject(id) : new Icon(icon, iconSetConfig);
+       return !icon ? announceIdNotFound(id) : new Icon(icon, iconSetConfig);
+     }
+
+     function announceIdNotFound(id) {
+       var msg = 'icon ' + id + ' not found';
+      $log.warn(msg);
+
+       return $q.reject(msg || id);
      }
    }
 
@@ -468,22 +472,7 @@
        .get(url, { cache: $templateCache })
        .then(function(response) {
          return angular.element('<div>').append(response.data).find('svg')[0];
-       });
-   }
-
-   /**
-    * User did not specify a URL and the ID has not been registered with the $mdIcon
-    * registry
-    */
-   function announceIdNotFound(id) {
-     var msg;
-
-     if (angular.isString(id)) {
-       msg = 'icon ' + id + ' not found';
-       $log.warn(msg);
-     }
-
-     return $q.reject(msg || id);
+       }).catch(announceNotFound);
    }
 
    /**

src/components/icon/iconService.spec.js

@@ -11,6 +11,7 @@ describe('mdIcon service', function() {
     $mdIconProvider
       .icon('android'     , 'android.svg')
       .icon('c2'          , 'c2.svg')
+      .icon('notfound'    ,'notfoundicon.svg')
       .iconSet('social'   , 'social.svg' )
       .iconSet('notfound' , 'notfoundgroup.svg' )
       .defaultIconSet('core.svg');
@@ -26,6 +27,7 @@ describe('mdIcon service', function() {
     $templateCache.put('c2.svg'     , '<svg><g id="c2" class="override"></g></svg>');
 
     $httpBackend.whenGET('notfoundgroup.svg').respond(404, 'Cannot GET notfoundgroup.svg');
+    $httpBackend.whenGET('notfoundicon.svg').respond(404, 'Cannot GET notfoundicon.svg');
 
   }));
 
@@ -104,7 +106,7 @@ describe('mdIcon service', function() {
     });
 
     describe('icon set URL is not found', function() {
-      it('should throw Error', function() {
+      it('should log Error', function() {
         var msg;
         try {
           $mdIcon('notconfigured')
@@ -119,8 +121,8 @@ describe('mdIcon service', function() {
       });
     });
 
-    describe('icon is not found', function() {
-      it('should throw Error', function() {
+    describe('icon group is not found', function() {
+      it('should log Error', function() {
         var msg;
         try {
           $mdIcon('notfound:someIcon')
@@ -135,6 +137,15 @@ describe('mdIcon service', function() {
       });
     });
 
+    describe('icon is not found', function() {
+      it('should not throw Error', function() {
+        expect(function(){
+          $mdIcon('notfound');
+
+          $httpBackend.flush();
+        }).not.toThrow();
+      });
+    });
   });
 
   function updateDefaults(svg) {