julia> import FileIO

julia> FileIO.save(FileIO.Stream(FileIO.format"BSON", IOBuffer()), Dict(:hey=>3))
Error encountered while saving nothing.

Fatal error:
ERROR: MethodError: no method matching bson(::Nothing, ::Dict{Symbol,Int64})
Closest candidates are:
  bson(::IO, ::AbstractDict) at /Users/goretkin/.julia/dev/BSON/src/write.jl:81
  bson(::String, ::AbstractDict) at /Users/goretkin/.julia/dev/BSON/src/write.jl:83
Stacktrace:
 [1] handle_error(::MethodError, ::Stream{DataFormat{:BSON},Base.GenericIOBuffer{Array{UInt8,1}}}) at /Users/goretkin/.julia/dev/FileIO/src/error_handling.jl:82
 [2] handle_exceptions(::Array{Any,1}, ::String) at /Users/goretkin/.julia/dev/FileIO/src/error_handling.jl:77
 [3] #save#30(::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::typeof(save), ::Formatted, ::Any) at /Users/goretkin/.julia/dev/FileIO/src/loadsave.jl:211
 [4] save(::Formatted, ::Any) at /Users/goretkin/.julia/dev/FileIO/src/loadsave.jl:194
 [5] top-level scope at none:0