Added error handling

include/cmd/cmd_touch.hpp

@@ -15,7 +15,7 @@ namespace fsh {
         virtual void run(std::istream& in, std::ostream& out, ArgManager& args) override {
             auto name = *(args.get<std::string>(0));
             if (std::ifstream(name, std::ios::in).good() || !std::ofstream(name, std::ios::out).is_open()) {
-                throw std::runtime_error("File exists");
+                throw util::FileExistsError();
             }
         }
     };