First time running ksv on a simple fmt breaks?

[shiftre]

4046010217 (of class java.lang.Long)
Compilation OK
C:/Ruby24-x64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require': no implicit conversion of nil into String (TypeError)
        from C:/Ruby24-x64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/kaitai-struct-visualizer-0.5/lib/kaitai/struct/visualizer/visualizer_main.rb:31:in `block in compile_format'
        from C:/Ruby24-x64/lib/ruby/2.4.0/tmpdir.rb:89:in `mktmpdir'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/kaitai-struct-visualizer-0.5/lib/kaitai/struct/visualizer/visualizer_main.rb:10:in `compile_format'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/kaitai-struct-visualizer-0.5/lib/kaitai/struct/visualizer/visualizer.rb:18:in `initialize'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/kaitai-struct-visualizer-0.5/bin/ksv:19:in `new'
        from C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/kaitai-struct-visualizer-0.5/bin/ksv:19:in `<top (required)>'
        from C:/Ruby24-x64/bin/ksv:22:in `load'
        from C:/Ruby24-x64/bin/ksv:22:in `<main>'

meta:
  id: fmt
  application: fmt
  endian: le
seq:
  - id: magic
    contents: [0xdeadbeef]
  - id: static
    contents: [0x56000000, 0x00000000, 0x33000000, 0xdeadcode]
  - id: BaseChunk
    type: u4

Am I missing something?

[shiftre]

It seem to be a syntax error, while having no idea how to confirm that, (the compilation says OK), hm.

[GreyCat]

• Judging by the error messages, you're probably using kaitai-struct-visualizer-0.5, and probably a more modern compiler (0.7?). Unfortunately, we haven't updated gems quite a long time, so if you want to use ksv, please install it from GitHub repo now.
• There are indeed two problems with your ksy:
  • id: BaseChunk is not a valid identifier; generally, one's expected to write lower_underscore_case identifiers, they would be formatted automatically according to the target language standards
  • contents key is to specify byte arrays, and [0xdeadbeef] (and similar declarations) is clearly not a byte. So, you've probably meant either [0xde, 0xad, 0xbe, 0xef] or [0xef, 0xbe, 0xad, 0xde], depending on representation of that integer (likely the latter, as you've specified endian: le).