Hello bizschumacher,
Thank you for submitting your crash. By looking up the report in our system, it seems that this is the main message that the crash is giving:
Assertion failed: InPos <= Size [File:D:\Build\++UE4+Release-4.13+Compile\Sync\Engine\Source\Runtime\Core\Private\HAL\FileManagerGeneric.cpp] [Line: 617] Attempted to seek past the end of file (156468/404), file: C:/Users//Documents/Unreal Projects//Content/Materials/Floors/M_Wood_Floor_Walnut_Polished.uasset. The file is most likely corrupt.
It looks like the file M_Wood_Floor_Walnut_Polished.uasset may be corrupt. Can you try removing it from the project’s directory to see if the project will open then? If you’d like to be able to see these crash messages in the future, you can get the debugging symbols required from the Epic Games Launcher by clicking the dropdown beside your engine version, selecting “Options” and checking “Editor symbols for debugging”.
Hope this helps!