WWAE_keras.py.TypeError: 'NoneType' object is not subscriptable

[jackliuhang]

Traceback (most recent call last):
File "", line 1, in
File "D:\pychrom\PyCharm Community Edition 2019.1.2\helpers\pydev_pydev_bundle\pydev_umd.py", line 197, in runfile
pydev_imports.execfile(filename, global_vars, local_vars) # execute the script
File "D:\pychrom\PyCharm Community Edition 2019.1.2\helpers\pydev_pydev_imps_pydev_execfile.py", line 18, in execfile
exec(compile(contents+"\n", file, 'exec'), glob, loc)
File "D:/pychormproject/venv/endtoend/wwae_keras/test1/WWAE_keras.py", line 93, in
callbacks=[tensorboard, callback_obj])
File "D:\anaconda3\envs\tensorflow\lib\site-packages\tensorflow\python\keras\engine\training.py", line 880, in fit
validation_steps=validation_steps)
File "D:\anaconda3\envs\tensorflow\lib\site-packages\tensorflow\python\keras\engine\training_arrays.py", line 370, in model_iteration
callbacks.on_epoch_end(epoch, epoch_logs, mode=mode)
File "D:\anaconda3\envs\tensorflow\lib\site-packages\tensorflow\python\keras\callbacks.py", line 251, in on_epoch_end
callback.on_epoch_end(epoch, logs)
File "D:\pychormproject\venv\endtoend\wwae_keras\test1\utils.py", line 41, in on_epoch_end
inp_stack = self.validation_data[0][:3]
TypeError: 'NoneType' object is not subscriptable