This message comes from the CPMaker.cp code where it is trying to read your project file and cannot find a target it knows about. If you point at your project in the FINDER and say show package contents. You will see a number of files in there if you open the pbxproj file (in a text editor) and look for the section PBXFileReference you will see all the files in your build. In there it has to find the string explicitFileType = "compiled.mach-o.executable" and that is the target executable for this project. If you aren't building that sort of thing then the program is a little confused and fails with this error.
You can see this search in the CPMake.cp file in the method
void CMaker::gatherline(). If you are not building a dylib or command line executable then PBTOMAKE will not find an executable it understands. If you are trying to build something else then send me a note directly (email@example.com) and we can see if this is possible.