Truncated Wizard state completely breaks wizard

julia> BinaryBuilder.run_wizard()
┌ Warning: Opening file with JLD2.MmapIO failed, falling back to IOStream
└ @ JLD2 ~/.julia/packages/JLD2/cHcDY/src/JLD2.jl:287
┌ Error: EOFError()
└ @ BinaryBuilder.Wizard ~/.julia/packages/BinaryBuilder/wohhx/src/Wizard.jl:78

    o      `.
   o*o      \'-_               00000000: 01111111  .
     \\      \;"".     ,;.--*  00000001: 01000101  E
      \\     ,\''--.--'/       00000002: 01001100  L
      :=\--<' `""  _   |       00000003: 01000110  F
      ||\\     `" / ''--       00000004: 00000010  .
      `/_\\,-|    |            00000005: 00000001  .
          \\/     L
           \\ ,'   \
         _/ L'   `  \          Join us in the #binarybuilder channel on the
        /  /    /   /          community slack: https://julialang.org/slack/
       /  /    |    \
      "_''--_-''---__=;        https://github.com/JuliaPackaging/BinaryBuilder.jl

Welcome to the BinaryBuilder wizard.  We'll get you set up in no time.

            # Step 1: Select your platforms

Make a platform selection
 > All Supported Platforms
   Select by Operating System
   Fully Custom Platform Choice

ERROR: ArgumentError: attempted to truncate a file that was already open
Stacktrace:
  [1] jldopen(fname::String, wr::Bool, create::Bool, truncate::Bool, iotype::Type{JLD2.MmapIO}; fallback::Type{IOStream}, compress::Bool, mmaparrays::Bool, typemap::Dict{String, Any}, parallel_read::Bool)
    @ JLD2 ~/.julia/packages/JLD2/cHcDY/src/JLD2.jl:334
  [2] jldopen(fname::String, wr::Bool, create::Bool, truncate::Bool, iotype::Type{JLD2.MmapIO})
    @ JLD2 ~/.julia/packages/JLD2/cHcDY/src/JLD2.jl:301
  [3] jldopen(fname::String, mode::String; iotype::Type, kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ JLD2 ~/.julia/packages/JLD2/cHcDY/src/JLD2.jl:439
  [4] jldopen(fname::String, mode::String)
    @ JLD2 ~/.julia/packages/JLD2/cHcDY/src/JLD2.jl:433
  [5] jldopen(::Function, ::String, ::Vararg{String}; kws::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ JLD2 ~/.julia/packages/JLD2/cHcDY/src/loadsave.jl:2
  [6] jldopen
    @ ~/.julia/packages/JLD2/cHcDY/src/loadsave.jl:1 [inlined]
  [7] save_wizard_state (repeats 2 times)
    @ ~/.julia/packages/BinaryBuilder/wohhx/src/Wizard.jl:33 [inlined]
  [8] run_wizard(state::Nothing)
    @ BinaryBuilder.Wizard ~/.julia/packages/BinaryBuilder/wohhx/src/Wizard.jl:126
  [9] run_wizard()
    @ BinaryBuilder.Wizard ~/.julia/packages/BinaryBuilder/wohhx/src/Wizard.jl:87
 [10] top-level scope
    @ REPL[1]:1
JuliaPackaging / BinaryBuilder.jl

Truncated Wizard state completely breaks wizard #1292
