Failed to set resource image when switching slides and playing animations

STEPS TO REPRODUCE:
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1.  Compile and run the demo(TestApp.zip)
2.  Press keyboard 1 according to the prompts to run the program
3.  Observe the display of gear in the window.

EXPECTED RESULT:
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       Every time the gear is changed, the setAttribute method is called to set two images to display as the current gear and the previous gear. And then slide change is triggered.

       Follow the testing steps, The expected result is gradual transition from  d gear to p, wait for 2 seconds, p to b(instant) , and then gradually transition from b to d, Loop according to this logic.

ACTUAL RESULT:
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       Failed to set image assets.  

        In the testing step, there is no interval between sending gears B and D, so under normal circumstances, it is impossible to observe the two situations in the above pictures.

EPRODUCIBILITY (%):
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100% reproduction within 5 minutes