error handling for openscop input

main.cpp

@@ -30,6 +30,10 @@ int main() {
 
 
     FILE *fp = fopen("acc.openscop", "r");
+    if(!fp) {
+        std::cerr << "openscop read failed\n";
+        return -1;
+    }
     scop = osl_scop_read(fp);
     //osl_scop_dump(stdout, scop);