Added an error to avoid an uninitialized value

src/tools/SwitchingFunction.cpp

@@ -278,6 +278,11 @@ double SwitchingFunction::inverse( const double& val ) const {
   double ival;  
 
   if( type==smap ){
+// I add this error because I do not know how to compute ival
+// previously this line was just missing
+// In this manner at least we are should that it cannot happen that
+// an uninitialized ival is used
+    plumed_merror("cannot compute ival in this case");
   } else if(type==rational){
       ival=1.1;
       for(unsigned i=0;;++i){