This error is caused by a prop with an incorrect "collisions" key setting. Not all props have physics meshes, so you can't select "vphysics". You have to either use the "use bounding box" or "not solid" options. This isn't caused by nonsense entities, it's caused by an entity with no defined type (ie. prop_physics or light.) I don't know if these will show up with Hammer's error checker or not, but they will be obvious because they'll be small red/white squares in the editor. This is an engine bug, not a map problem. The compile tools will create one instance of info_ladder for every ladder brush contained in the map. The info_ladder will contain the bounding box coordinates for a specific brush based ladder in the map. If you decompile a map, you may notice that no brush ladder entities exist, but there will be a ton of info_ladder entities at the world origin 0,0,0. Related to error above of null named entities.