Agreed. Author is trying to mix paradigms. Simplest approach if they want local handling and non-propagation of errors is to just have the file holder not check for open success, and check that manually after construction. Then you get guaranteed closure of file no matter how the function is exited.

  class File_handle {
      FILE *p;
  public:
      File_handle(const char *pp, const char *r)  { p = fopen(pp, r); }
      ~File_handle() { if ( p ) fclose(p); }
      FILE* file() const { return p; }
  };
  
  
  void f(string s)
  {
      File_handle fh { s, "r"};
      if ( fh.file() == NULL ) {
          fprintf(stderr, "failed to open file '%s', error=%d\n", p, errno);
          return;
      }
      // use fh
  }