Apple, it's time! Recall every MacBook Pro unibody affected and replace the logic board with a new, redesigned one that does not have the factory defect / design problem.

My Apple MacBook Pro Retina Mid 2014 started to Randomly Shutdown especially when idle. This happens no matter whether the machine is on battery power or connected to the charger. I have noticed a trend around this problem where it only happens when the machine idles. 

1. I reseted the SMC a couple of times.

2. Reloaded High Sierra from a USB image that I downloaded.

3. Replaced the Thermal Paste of the CPU and GPU

4. Tried different chargers / power cables

As soon as you run a command in Terminal "yes >/dev/null &" where it keeps the CPU or at least one of the cores engaged then it does not happen. There is even software available from a third party that suggests to resolve this problem which can be bought for $10.

A quick search on Google shows lots of results on Forums explaining the same symptoms and issues that users experience. Users also indicated that this only happens on Mac OS and not when you install Windows or Linux on the same machine. 

The event logs shows a generic -128 error on shutdown which is not self explanatory.

Just read the comments on this video as an example to the problem: https://www.youtube.com/watch?v=DsHi9ICg_lg