`StructTypes.x` is not defined

@kshyatt

│┌ @ C:\.julia\packages\JSON3\CpNms\src\structs.jl:32 JSON3.:(var"#read#16")(false, pairs(NamedTuple()::NamedTuple{(), Tuple{}})::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, #self#::typeof(JSON3.read), str::String, _3::Type{TrinityApi._PipeCommunication.Data})
││┌ @ C:\.julia\packages\JSON3\CpNms\src\structs.jl:40  = JSON3.read(JSON3.StructType(T::Type{TrinityApi._PipeCommunication.Data})::StructTypes.UnorderedStruct, buf::Base.CodeUnits{UInt8, String}, pos::Int64, len::Int64, b::UInt8, T::Type{TrinityApi._PipeCommunication.Data})
│││┌ @ C:\.julia\packages\JSON3\CpNms\src\structs.jl:566 JSON3.:(var"#read#50")(pairs(NamedTuple()::NamedTuple{(), Tuple{}})::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, #self#::typeof(JSON3.read), _2::StructTypes.UnorderedStruct, buf::Base.CodeUnits{UInt8, String}, pos::Int64, len::Int64, b::UInt8, _7::Type{TrinityApi._PipeCommunication.Data})
││││┌ @ C:\.julia\packages\JSON3\CpNms\src\structs.jl:617 (JSON3.StructTypes).applyfield::typeof(StructTypes.applyfield)(c, T::Type{TrinityApi._PipeCommunication.Data}, key::Symbol)
│││││┌ @ C:\.julia\packages\StructTypes\AK4aM\src\StructTypes.jl:891 StructTypes.x
││││││ `StructTypes.x` is not defined
│││││└──────────────────────────────────────────────────────────────

Start by reproducing the reported failure with the TrinityApi._PipeCommunication.Data type and inspect StructTypes.jl at src/StructTypes.jl:891, where the stack trace reports that StructTypes.x is undefined. Compare that call with the JSON3 stack frames in src/structs.jl, then define completion as a confirmed diagnosis and a regression-tested resolution for this deserialization error.