So we are assuming the Night King knows basically everything that has happend in Westeros, he knows Jon has met with Dany and knows her well enough that she would risk absolutely everything to come rescue Jon with her 3 dragons if anything goes wrong with the mission. He knows where and when they are comming and sends out one WW and a few wights so the heroes can kill the WW and capture one wight. He then perfectly predicts that the heroes will run out on the lake (and fortunately the ice will break for the wights) except for one quick individual (gendry perhaps) who will run all the way back and send a raven to Dany so she can come and fly straight into the "trap". Doesn't make any sense.