Lack of error message when a function is passed as an argument in a component in the initial layout

Dash Python
1

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We do our best to catch bugs during the release process, but we rely on your help to find the ones that slip through.

Describe your context

  • pip list | grep dash below
dash                      2.9.3
dash-ag-grid              2.0.0a4
dash-bootstrap-components 1.4.0
dash-core-components      2.0.0
dash-design-kit           1.6.8
dash-enterprise-auth      0.0.5
dash-html-components      2.0.0
dash-iconify              0.1.2
dash-mantine-components   0.12.1
dash-snapshots            2.2.0
dash-table                5.0.0

Describe the bug

Passing a function as an argument (by mistake) causes an “Error Loading Layout” on the webpage with no description of the error.
example code:

import dash
from dash import dcc, html, Input, Output, State

app = dash.Dash()

def example_fun():
    return

server = app.server
app.layout = html.Div([dcc.Graph(figure=example_fun)])    # should be example_fun()

if __name__ == "__main__":
    app.run_server(debug=True, port=8050)

Expected behavior

There should be a more descriptive error message such as “functions not supported as arguments”