Bonito.jl: Page() fails in Pluto

Code in the Pluto cell

using JSServe
Page(listen_port=9876)

OS: MacOS 11.5.2 julia: 1.6.0 JSServe: 1.2.3 Pluto: 0.16.0

Error message

Failed to show value:
HTTP.ExceptionRequest.StatusError(503, "GET", "http://127.0.0.1:9876/assetserver/6160a0f5a8831ce6c083fb16b324f82b26630fcd-JSServe.js", HTTP.Messages.Response:
"""
HTTP/1.1 503 Service Unavailable
Connection: close
Proxy-Connection: close
Content-Length: 0
""")
var"#request#1"(::Base.Iterators.Pairs{Symbol, Union{Nothing, Integer}, Tuple{Symbol, Symbol, Symbol}, NamedTuple{(:iofunction, :reached_redirect_limit, :readtimeout), Tuple{Nothing, Bool, Int64}}}, ::typeof(HTTP.request), ::Type{HTTP.ExceptionRequest.ExceptionLayer{HTTP.ConnectionRequest.ConnectionPoolLayer{HTTP.TimeoutRequest.TimeoutLayer{HTTP.StreamRequest.StreamLayer{Union{}}}}}}, ::URIs.URI, ::Vararg{Any, N} where N)@ExceptionRequest.jl:22
(::Base.var"#70#71#73"{ExponentialBackOff, HTTP.RetryRequest.var"#2#3"{Bool, HTTP.Messages.Request}, typeof(HTTP.request)})(::Base.Iterators.Pairs{Symbol, Union{Nothing, Integer}, Tuple{Symbol, Symbol, Symbol}, NamedTuple{(:iofunction, :reached_redirect_limit, :readtimeout), Tuple{Nothing, Bool, Int64}}}, ::Base.var"#70#72"{Base.var"#70#71#73"{ExponentialBackOff, HTTP.RetryRequest.var"#2#3"{Bool, HTTP.Messages.Request}, typeof(HTTP.request)}}, ::Type, ::Vararg{Any, N} where N)@error.jl:301
#request#1@RetryRequest.jl:44[inlined]
var"#request#1"(::VersionNumber, ::String, ::Nothing, ::Nothing, ::Base.Iterators.Pairs{Symbol, Integer, Tuple{Symbol, Symbol, Symbol}, NamedTuple{(:reached_redirect_limit, :readtimeout, :retries), Tuple{Bool, Int64, Int64}}}, ::typeof(HTTP.request), ::Type{HTTP.MessageRequest.MessageLayer{HTTP.RetryRequest.RetryLayer{HTTP.ExceptionRequest.ExceptionLayer{HTTP.ConnectionRequest.ConnectionPoolLayer{HTTP.TimeoutRequest.TimeoutLayer{HTTP.StreamRequest.StreamLayer{Union{}}}}}}}}, ::String, ::URIs.URI, ::Vector{Pair{SubString{String}, SubString{String}}}, ::Vector{UInt8})@MessageRequest.jl:66
var"#request#1"(::Base.Iterators.Pairs{Symbol, Integer, Tuple{Symbol, Symbol, Symbol}, NamedTuple{(:reached_redirect_limit, :readtimeout, :retries), Tuple{Bool, Int64, Int64}}}, ::typeof(HTTP.request), ::Type{HTTP.BasicAuthRequest.BasicAuthLayer{HTTP.MessageRequest.MessageLayer{HTTP.RetryRequest.RetryLayer{HTTP.ExceptionRequest.ExceptionLayer{HTTP.ConnectionRequest.ConnectionPoolLayer{HTTP.TimeoutRequest.TimeoutLayer{HTTP.StreamRequest.StreamLayer{Union{}}}}}}}}}, ::String, ::URIs.URI, ::Vector{Pair{SubString{String}, SubString{String}}}, ::Vector{UInt8})@BasicAuthRequest.jl:28
var"#request#1"(::Int64, ::Bool, ::Base.Iterators.Pairs{Symbol, Int64, Tuple{Symbol, Symbol}, NamedTuple{(:readtimeout, :retries), Tuple{Int64, Int64}}}, ::typeof(HTTP.request), ::Type{HTTP.RedirectRequest.RedirectLayer{HTTP.BasicAuthRequest.BasicAuthLayer{HTTP.MessageRequest.MessageLayer{HTTP.RetryRequest.RetryLayer{HTTP.ExceptionRequest.ExceptionLayer{HTTP.ConnectionRequest.ConnectionPoolLayer{HTTP.TimeoutRequest.TimeoutLayer{HTTP.StreamRequest.StreamLayer{Union{}}}}}}}}}}, ::String, ::URIs.URI, ::Vector{Pair{SubString{String}, SubString{String}}}, ::Vector{UInt8})@RedirectRequest.jl:28
#request#1@TopRequest.jl:15[inlined]
var"#request#9"(::Vector{Pair{SubString{String}, SubString{String}}}, ::Vector{UInt8}, ::Nothing, ::Base.Iterators.Pairs{Symbol, Int64, Tuple{Symbol, Symbol}, NamedTuple{(:readtimeout, :retries), Tuple{Int64, Int64}}}, ::typeof(HTTP.request), ::String, ::String, ::Vector{Pair{SubString{String}, SubString{String}}}, ::Vector{UInt8})@HTTP.jl:330
#get#17@HTTP.jl:407[inlined]
warmup(::JSServe.Server)@server.jl:160
var"#Server#18"(::Bool, ::JSServe.Routes, ::JSServe.Routes, ::Type{JSServe.Server}, ::JSServe.App, ::String, ::Int64)@server.jl:234
get_server()@server.jl:311
show(::IOContext{IOBuffer}, ::MIME{Symbol("text/html")}, ::JSServe.Page)@display.jl:89
show_richest(::IOContext{IOBuffer}, ::Any)@PlutoRunner.jl:783
var"#sprint_withreturned#32"(::IOContext{Base.DevNull}, ::Int64, ::typeof(Main.PlutoRunner.sprint_withreturned), ::Function, ::JSServe.Page)@PlutoRunner.jl:720
format_output_default(::Any, ::Any)@PlutoRunner.jl:644
#format_output#21@PlutoRunner.jl:661[inlined]
formatted_result_of(::Base.UUID, ::Bool, ::Nothing, ::Module)@PlutoRunner.jl:577
top-level scope@none:1