Crashes when there are playerdatas other than .dat and .dat_old

[GuiTaek]

When there is a file with format <UUID>-1111111111111111111.dat inside the playerdata (happens when you open a file in this folder while the game is trying to save the playerdata) and entering the pocket dimension when the player is saved outside the pocket dimension (e.g. because of restart of the game), the game crashes.

[GuiTaek]

Reason for this this file not being expected. This shouldn't happen while usual playing. Usually this would only be present when entering a pocket dimension first time in your world, however, Issue 9 triggers the finding of a new pocket dimension every time, the player is saved outside a pocket dimension

[GuiTaek]

I solved this issue deeper than probably necessary:

• no (catched) crash when a file has unexpected filename
• the files with above format will be ignored