Various issues

[errael]

1. '<<' not handled
2. echo 'output:' 3
   error
3. finish
   panics
4. export var v1

   unreachable code "VarCommand"
   

5. null handling issues

   vim9script
   var x = null_list
   echo printf("null_string: '%s'", x)
   

   outputs

   null_string: 'v:null'
   

   In vim9 it outputs

   null_string: '[]'
   

6. Another null handling issue

   vim9script
   var x = null_list
   x += [3]
   echo printf("x: '%s'", x)
   

   in vim outputs

   x: '[3]'
   

   in neovim execution error

   line    4:
   E5108: Error executing lua /junk/install/local/share/nvim/runtime/lua/_vim9script.lua:572:
       attempt to perform arithmetic on local 'left' (a nil value)
   stack traceback:
           /junk/install/local/share/nvim/runtime/lua/_vim9script.lua:572: in function 'Plus'
           /src/tools/neovim/vim9jit/play/converted/nulls.lua:17: in function 'autoload'
           [string "luaeval()"]:1: in main chunk
   

7. working with classes

   vim9script
   class C
       def F(): string
           return 'foo'
       enddef
   endclass
   echo C.new().F()
   

   compiles/run time error

   E5108: Error executing lua /src/tools/neovim/vim9jit/play/converted/class.lua:21:
       attempt to index global 'C' (a nil value)
   stack traceback:
           /src/tools/neovim/vim9jit/play/converted/class.lua:21: in function 'autoload'
           [string "luaeval()"]:1: in main chunk
   

8. numeric/type issues

   vim9script
   def F(a: number): number
       return a / 2
   enddef
   echo F(3)
   

   vim outputs 1, vim9jit/neovim outputs 1.5