fix warning: hdunum int-long mismatch

data-access/engine/src/common/src/fits_header.cpp

@@ -321,7 +321,8 @@ void fits::header::open_fitsfile(std::string pathname, unsigned long hdunum, int
 
    if ( !fits_open_file(&fptr, pathname.c_str(), iomode, &status) )
    {
-      if( !fits_movabs_hdu(fptr, hdunum, NULL, &status) )
+      if(hdunum > INT_MAX) throw runtime_error("hdunum too big: " + to_string(hdunum));
+      if( !fits_movabs_hdu(fptr, (int)hdunum, NULL, &status) )
       {
          this->hdunum = hdunum;
          int hdutype = -1;