Nevermind, I poked at it until I fixed it!
I basically figured by the error code that it meant that a file wasn't in the right place, or the catagories.php was looking in the wrong place to find the productimagehandler.php, so I played around with it and walked away from it. Eventually I came back and opted at that point to go ahead and start the process from the beginning again. This time the error went away, woohoo!
Now I just have to figure out the rest of it...