Also today had a problem where I click on the bottom shipyard and got a null problem in the construction/refit section of the window. The title of the ship to be built is blank. An error message popped up but I didn't write it down.
I have to retract this bug, but this error was caused by another bug.
The reason I was getting a null error was because the ship the yard was tooled to work on was larger than the shipyard. The yard was 5000 tons, the ship design was originally 5000 tons but had become 5050 tons. When I looked into it I remembered another bug I occasionally come across.
My original design for the ship brought the "actual" tonnage right up to 5000 tons, with addition of some small fuel tanks (10 ton each). When I checked the design it had turned into 5005 actual tonnage. I've run into this before with other ships, all I do is remove one of the small fuel tanks, it subtracts 15 tons, and add the small tank back in which only adds 10 tons.