Multi-output callback error in tutorial

[Jakob]

On running the tutorial example on callbacks, I run into the following error:

┌ Error: error handling request │ exception = │ Invalid callback return value: The callback graph.figure is a multi-output. │ Expected the output type to be a list or tuple but got: │ {"layout":{"xaxis1":{"type":"log","title":"GDP Per Capita", [truncated because of long output] │ Stacktrace: │ [1] validate_callback_return(::Array{NamedTuple{(:id, :property),Tuple{String,String}},1}, ::Plot{Array{AbstractTrace,1},Layout{Dict{Symbol,Any}},Array{PlotlyFrame,1}}, ::Symbol) at C:\Users\Jakob\.julia\packages\Dash\OP7s2\src\handler\processors\callback.jl:81

Here's the code:

using DataFrames, Dash, DashHtmlComponents, DashCoreComponents, PlotlyJS, UrlDownload


df1 = DataFrame(urldownload("https://raw.githubusercontent.com/plotly/datasets/master/gapminderDataFiveYear.csv"))

years = unique(df1[!, :year])

app = dash()

app.layout = html_div() do
    dcc_graph(id = "graph"),
    dcc_slider(
        id = "year-slider-1",
        min = minimum(years),
        max = maximum(years),
        marks = Dict([Symbol(v) => Symbol(v) for v in years]),
        value = minimum(years),
        step = nothing,
    )
end

callback!(
    app,
    Output("graph", "figure"),
    Input("year-slider-1", "value"),
) do selected_year
    return Plot(
        df1[df1.year .== selected_year, :],
        Layout(
            xaxis_type = "log",
            xaxis_title = "GDP Per Capita",
            yaxis_title = "Life Expectancy",
            legend_x = 0,
            legend_y = 1,
            hovermode = "closest",
            transition_duration = 500
        ),
        x = :gdpPercap,
        y = :lifeExp,
        text = :country,
        group = :continent,
        mode = "markers",
        marker_size = 15,
        marker_line_color = "white",
    )
end

run_server(app, "0.0.0.0", debug = true)

I'm on Julia 1.5 and here's my environment status:

[1b08a953] Dash v0.1.3 [a03496cd] PlotlyBase v0.4.1 [f0f68f2c] PlotlyJS v0.14.0

[Jakob]

So on a fresh session and after restarting the computer the issues are gone - the package versions are the same, so not sure what caused it. Sorry for the false alarm!

[Alexandr Romanenko]

the issues are gone

@jfb-h This is good, because I have been trying to reproduce this error for several days now

Thank you for using Dash!

[Jakob]

Thanks for looking into it. If it happens again I'll try to narrow down the cause and let you know.