I tried to reproduce the crash, but the Cool VL Viewer properly reports a failure to decode the PSD image I used:
Also, I fail to see how you can accidentally select an image with an unrecognized format, since by default, and unless your force the filter to "all files", the file selector is passed a filter only allowing to select PNG, TGA, BMP and JPG files.
This said, the viewer must support TGA files, and since TGA files are without a "magic number" in their header (which is just a collection of pointers and size related numbers describing the image width, height, channels, etc), the viewer cannot recognize a random unsupported format from a TGA file and will attempt to load it as a TGA file anyway, which, depending on the values it finds in what it thinks is a legit TGA header, might lead to a crash. Some sanity checks are made, but they can't reasonably cover all possible cases.
Simply be more careful when overriding the file selector filter and trying to force the viewer to "digest" a format it doesn't support...
I will also note that this is in no way a Cool VL Viewer specific bug (so you should reproduce it with an official viewer and report it on the SL JIRA if you want it to get fixed some day).