It's couldn't access the template file, so I fixed it.
root@ce65675642c7:/# vgcal init
/usr/local/lib/ruby/3.0.0/fileutils.rb:1414:in `initialize': No such file or directory @ rb_sysopen - template-credentials.json (Errno::ENOENT)
from /usr/local/lib/ruby/3.0.0/fileutils.rb:1414:in `open'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:1414:in `copy_file'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:514:in `copy_file'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:433:in `block in cp'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:1597:in `block in fu_each_src_dest'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:1613:in `fu_each_src_dest0'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:1595:in `fu_each_src_dest'
from /usr/local/lib/ruby/3.0.0/fileutils.rb:432:in `cp'
from /usr/local/bundle/gems/vgcal-0.3.2/lib/vgcal/handlers/describer.rb:19:in `init'
from /usr/local/bundle/gems/thor-1.1.0/lib/thor/command.rb:27:in `run'
from /usr/local/bundle/gems/thor-1.1.0/lib/thor/invocation.rb:127:in `invoke_command'
from /usr/local/bundle/gems/thor-1.1.0/lib/thor.rb:392:in `dispatch'
from /usr/local/bundle/gems/thor-1.1.0/lib/thor/base.rb:485:in `start'
from /usr/local/bundle/gems/vgcal-0.3.2/lib/vgcal/handlers/describer.rb:168:in `<top (required)>'
from <internal:/usr/local/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from <internal:/usr/local/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from /usr/local/bundle/gems/vgcal-0.3.2/lib/vgcal.rb:8:in `<module:Vgcal>'
from /usr/local/bundle/gems/vgcal-0.3.2/lib/vgcal.rb:6:in `<top (required)>'
from <internal:/usr/local/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from <internal:/usr/local/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from /usr/local/bundle/gems/vgcal-0.3.2/exe/vgcal:3:in `<top (required)>'
from /usr/local/bundle/bin/vgcal:23:in `load'
from /usr/local/bundle/bin/vgcal:23:in `<main>'
root@ce65675642c7:/# vgcal init
Fix the __FIX_ME__ in /root/.vgcal/credentials.json and /root/.vgcal/.env
It's couldn't access the template file, so I fixed it.