Compile stage - Ruby giving out NoMethodError

[Chewbakka-Wakka]

After finding this software I was attempting to build an RPM from source to enable easy installation.
Standard autotools in use with gfortan compiler.
Read all the supporting compile docs, (using Fedora 38) I encounter these issues, note all RPM dependencies are met:

$ rpm -qa *gfortran
libgfortran-13.2.1-4.fc40.x86_64
gcc-gfortran-13.2.1-4.fc40.x86_64

$ rpm -qa ruby* | sort
ruby-3.2.2-183.fc40.x86_64
ruby-default-gems-3.2.2-183.fc40.noarch
ruby-devel-3.2.2-183.fc40.x86_64
ruby-libs-3.2.2-183.fc40.x86_64
rubygem-io-console-0.6.0-183.fc40.x86_64
rubygem-json-2.6.3-204.fc39.x86_64
rubygem-narray-0.6.1.1-28.fc39.x86_64
rubygem-psych-5.0.1-183.fc40.x86_64
rubygem-rdoc-6.5.0-183.fc40.noarch
rubygems-3.4.10-183.fc40.noarch
rubygems-devel-3.4.10-183.fc40.noarch
rubypick-1.1.1-19.fc39.noarch

./config/depf90:38:in block in <main>': undefined method exists?' for File:Class (NoMethodError)

fname = srcdir + "/" + fname unless(File.exists?(fname))
                                        ^^^^^^^^

Did you mean? exist?
from ./config/depf90:28:in each' from ./config/depf90:28:in

'
./config/depf90:38:in block in <main>': undefined method exists?' for File:Class (NoMethodError)

fname = srcdir + "/" + fname unless(File.exists?(fname))
                                        ^^^^^^^^

Did you mean? exist?
from ./config/depf90:28:in each' from ./config/depf90:28:in

'
/usr/bin/mkdir -p thirdparty/2stream
/usr/bin/mkdir -p /usr/include
/usr/bin/ruby ./config/depf90 "." libtwostream_la- "thirdparty/2stream/2stream_brdf_kernels.F90 thirdparty/2stream/2stream_brdf_supplement.F90 thirdparty/2stream/2stream_bvproblem.F90 thirdparty/2stream/2stream_inputs.F90 thirdparty/2stream/2stream_intensity.F90 thirdparty/2stream/2stream_la_solutions.F90 thirdparty/2stream/2stream_lc_bvproblem.F90 thirdparty/2stream/2stream_lc_jacobians.F90 thirdparty/2stream/2stream_lc_miscsetups.F90 thirdparty/2stream/2stream_lcs_master.F90 thirdparty/2stream/2stream_l_inputs.F90 thirdparty/2stream/2stream_lp_bvproblem.F90 thirdparty/2stream/2stream_lp_jacobians.F90 thirdparty/2stream/2stream_lp_miscsetups.F90 thirdparty/2stream/2stream_lps_master.F90 thirdparty/2stream/2stream_ls_brdf_kernels.F90 thirdparty/2stream/2stream_ls_brdf_supplement.F90 thirdparty/2stream/2stream_ls_bvproblem.F90 thirdparty/2stream/2stream_ls_jacobians.F90 thirdparty/2stream/2stream_lssl_jacobians.F90 thirdparty/2stream/2stream_lssl_sleave_supplement.F90 thirdparty/2stream/2stream_l_thermalsup.F90 thirdparty/2stream/2stream_l_writemodules.F90 thirdparty/2stream/2stream_master.F90 thirdparty/2stream/2stream_miscsetups.F90 thirdparty/2stream/2stream_Planckfunc.F90 thirdparty/2stream/2stream_sleave_routines.F90 thirdparty/2stream/2stream_sleave_supplement.F90 thirdparty/2stream/2stream_solutions.F90 thirdparty/2stream/2stream_Taylor.F90 thirdparty/2stream/2stream_thermalsup.F90 thirdparty/2stream/2stream_writemodules.F90" > thirdparty/2stream/2stream.deps.tmp && mv thirdparty/2stream/2stream.deps.tmp thirdparty/2stream/2stream.deps
./config/depf90:38:in block in <main>': undefined method exists?' for File:Class (NoMethodError)
...
Continues before ending in error: Bad exit status from /var/tmp/rpm-tmp.IPOEa7 (%build)
I also note in comments around Ruby code, that all the stages where Ruby is used could be replaced with Python.