Fixed weird error message when CSP library files do not exist

Author: cschreib

src/fast++-gridder.cpp

@@ -258,6 +258,7 @@ public :
     bool read(std::string filename) {
         std::string state;
         try {
+            state = "open file";
             file_wrapper lib(filename);
 
             // The file might have been written with a different endianess...