This particular flow can only really occur if your OBS Profile has a super invalid resolution.
OBS Studio's settings can be found in the following location:
WinKey+R > %APPDATA%\obs-studio\basic\profiles\<profilename>\basic.ini
Look for a section called [Video] and set it to something like:
[Video]
BaseCX=1920
BaseCY=1080
OutputCX=1280
OutputCY=720
Then post below with the values that *were* in there so that we can look into protecting against it.