Only subset of YAML supported and raises on encrypt `no implicit conversion of Hash into Integer (TypeError)`

Problem

When calling encrypt with some YAML it raises. This means only a subset of YAML is supported, but the file I am trying to encrypt has a structure like this:

list:
  -
    item: 1
    details: detail1
  -
    item: 2
    details: detail2

The exception raised is:

/ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:84:in `[]=': no implicit conversion of Hash into Integer (TypeError)
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:84:in `block in encrypt_values'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:80:in `each'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:80:in `encrypt_values'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:85:in `block in encrypt_values'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:80:in `each'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:80:in `encrypt_values'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:65:in `encrypt_data'
    from /ruby/3.0.2/lib/ruby/gems/3.0.0/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:51:in `encrypt'

With this debug call stack information:

encrypt_values(data={"list"=>[{"item"=>1, "details"=>"detail1"}, {"item"=>2, "details"=>"detail2"}]}, original_data=)
  data[list] = [{"item"=>1, "details"=>"detail1"}, {"item"=>2, "details"=>"detail2"}] (Array)
encrypt_values(data=[{"item"=>1, "details"=>"detail1"}, {"item"=>2, "details"=>"detail2"}], original_data=)
  data[{"item"=>1, "details"=>"detail1"}] = nil (NilClass)

Reproduction

require "diffcrypt"
key = "a5c51953b9c43c3f0e1dff3d5761c7d0000aefd85903d428e01bdb6d5916dc01"
text = "list:\n  -\n    item: 1\n    details: detail1\n  -\n    item: 2\n    details: detail2\n"
encryptor = Diffcrypt::Encryptor.new(key)
encryptor.encrypt(text)

I'm getting encryptor.rb:81:in `[]=': no implicit conversion of String into Integer (TypeError); potentially a similar root cause.

The yml file contains some unorthodox keys such as:

foo:
  - "123123"
  - "4345354"

Likely this is rather an abuse of Rails credentials, would still be nice if I could add diffcrypt though :)

Full stack trace:

34: from bin/rails:4:in `<main>'
33: from 2.7.7/gems/activesupport-6.0.6.1/lib/active_support/dependencies.rb:324:in `require'
32: from 2.7.7/gems/activesupport-6.0.6.1/lib/active_support/dependencies.rb:291:in `load_dependency'
31: from 2.7.7/gems/activesupport-6.0.6.1/lib/active_support/dependencies.rb:324:in `block in require'
30: from 2.7.7/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
29: from 2.7.7/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
28: from 2.7.7/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
27: from 2.7.7/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
26: from 2.7.7/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
25: from 2.7.7/gems/railties-6.0.6.1/lib/rails/commands.rb:18:in `<main>'
24: from 2.7.7/gems/railties-6.0.6.1/lib/rails/command.rb:46:in `invoke'
23: from 2.7.7/gems/railties-6.0.6.1/lib/rails/command/base.rb:69:in `perform'
22: from 2.7.7/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
21: from 2.7.7/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
20: from 2.7.7/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
19: from 2.7.7/gems/railties-6.0.6.1/lib/rails/commands/credentials/credentials_command.rb:32:in `edit'
18: from 2.7.7/gems/railties-6.0.6.1/lib/rails/command/helpers/editor.rb:26:in `catch_editing_exceptions'
17: from 2.7.7/gems/railties-6.0.6.1/lib/rails/commands/credentials/credentials_command.rb:33:in `block in edit'
16: from 2.7.7/gems/railties-6.0.6.1/lib/rails/commands/credentials/credentials_command.rb:67:in `change_credentials_in_system_editor'
15: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/rails/encrypted_configuration.rb:72:in `change'
14: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/rails/encrypted_configuration.rb:87:in `writing'
13: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/rails/encrypted_configuration.rb:57:in `write'
12: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/rails/encrypted_configuration.rb:104:in `encrypt'
11: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:51:in `encrypt'
10: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:65:in `encrypt_data'
9: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:79:in `encrypt_values'
8: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:79:in `each'
7: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:82:in `block in encrypt_values'
6: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:79:in `encrypt_values'
5: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:79:in `each'
4: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:82:in `block in encrypt_values'
3: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:79:in `encrypt_values'
2: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:79:in `each'
1: from 2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:81:in `block in encrypt_values'
2.7.7/gems/diffcrypt-0.6.1/lib/diffcrypt/encryptor.rb:81:in `[]=': no implicit conversion of String into Integer (TypeError)

diffcrypt / diffcrypt-ruby

Only subset of YAML supported and raises on encrypt `no implicit conversion of Hash into Integer (TypeError)` #122

Problem

Reproduction