--with-rt=SPHM1RT_1 doesn't compile

rt/SPHM1RT/rt_cooling.c: In function 'rt_do_thermochemistry':
rt/SPHM1RT/rt_cooling.c:212:50: error: array subscript 1 is above array bounds of 'double[1]' [-Werror=array-bounds]
  212 |     sigmalist[1][0] = rt_props->sigma_cross_cgs_H[1];
      |                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from rt/SPHM1RT/rt_cooling.h:27,
                 from rt/SPHM1RT/rt_cooling.c:33:
rt/SPHM1RT/rt_properties.h:122:10: note: while referencing 'sigma_cross_cgs_H'
  122 |   double sigma_cross_cgs_H[RT_NGROUPS];
      |          ^~~~~~~~~~~~~~~~~
rt/SPHM1RT/rt_cooling.c:213:50: error: array subscript 2 is above array bounds of 'double[1]' [-Werror=array-bounds]
  213 |     sigmalist[2][0] = rt_props->sigma_cross_cgs_H[2];
      |                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from rt/SPHM1RT/rt_cooling.h:27,
                 from rt/SPHM1RT/rt_cooling.c:33:
rt/SPHM1RT/rt_properties.h:122:10: note: while referencing 'sigma_cross_cgs_H'
  122 |   double sigma_cross_cgs_H[RT_NGROUPS];
      |          ^~~~~~~~~~~~~~~~~

The StromgrenSphere_2D/README instructs users to configure using --with-SPHM1RT_1 though.