A potential workaround if your game crashes often when in Fleet managment window or anytime related to the fleet is this. HG needs to fix it, but in the meantime if you don't mind try this:

You have these crashes probably due to the new freighter you were given for free and the routine was bugged and carried over to live version. The versions concerned are 1.58 or exp-1.58+

Or you wait until next regular update or try this as a workaround:

There is a tool allowing you to edit your savegame. Use it and tweak your credits, buy a new freighter, save the game and reload. It should be solved now with no further crashes. The tool is:
https://github.com/goatfungus/NMSSaveEditor

Thanks to feedback if it works or not.

Good luck!