def validation_epoch_end(self, outputs):
    	val_loss = torch.stack([x['val_loss'] for x in outputs]).mean()
    	log = {'avg_val_loss': val_loss}
    	return {'log': log, 'val_loss': log}

When i am using the above method in pytorh lightning it throws me an error TypeError: cannot unpack non-iterable NoneType object
This is happening before the last step of validation data. I can see that the return {'log': log, 'val_loss': log} is where the error is but couldnt actually find out whats wrong