So recently I've installed Fallout 4. I purchased the game obviously. The thing is that, the night when I was downloading the game, the power went out, and my computer shut down with it. The morning, I fired up the computer again, and I saw the download bar at around 17 GB. I had the same issue with another game, and the singleplayer campaign didn't quite work. At around 10 hours of playing the game, I saw that at the mission "Unlikely Valentine" when Skinny Malone appears, I left the station, but Nick Valentine was not there when I exited. When I entered back, I saw Malone and the two triggermens near, but Nick Valentine was not there. I looked at my Pip-Boy to see if I completed the quest, but it turns out that I didn't. My saves are go over that scene. Is this a bug, or beacause of the file corruption?
Could be either one.
If you're using a PC, one way you can rule out game-file corruption is to go into the game properties in steam (right-click the game > properties), go to the local files tab, and click "Verify Integrity of Game Cache."
Of course, this method will not rule out a corrupted save file, which is an absolute possibility.
Also, AIs can get teleported into walls or go all the way back to their origin in an instant for no reason. You may try to revert to a save where Nick was with you and leave the vault a different way.