mod: 1. change playback mode getter 2. fix playback mode test typo

SDWebImage/Core/SDAnimatedImageView.m

@@ -248,6 +248,9 @@
 }
 
 - (SDAnimatedImagePlaybackMode)playbackMode {
+    if (!_initFinished) {
+        return SDAnimatedImagePlaybackModeNormal; // Default mode is normal
+    }
     return _playbackMode;
 }
 

Tests/Tests/SDAnimatedImageTest.m

@@ -602,7 +602,7 @@ static BOOL _isCalled;
     expect(SDImageAPNGTestCoder.isCalled).equal(YES);
 }
 
-- (void)test31AnimatedImagePlaybackModeReverse {
+- (void)test30AnimatedImagePlaybackModeReverse {
     XCTestExpectation *expectation = [self expectationWithDescription:@"test SDAnimatedImageView playback reverse mode"];
     
     SDAnimatedImageView *imageView = [SDAnimatedImageView new];