Python Dash中的多个下拉列表出错

import dash
from dash import dcc, html
from dash.dependencies import Input, Output

app = dash.Dash(__name__)

app.layout = html.Div([
    dcc.Dropdown(
        id='dropdown-1',
        options=[{'label': i, 'value': i} for i in ['A', 'B', 'C']],
        value='A'
    ),
    dcc.Dropdown(
        id='dropdown-2',
        options=[],
        value=None
    ),
    dcc.Store(id='intermediate-value')
])

@app.callback(
    Output('intermediate-value', 'data'),
    Input('dropdown-1', 'value')
)
def update_intermediate_value(selected_value):
    return {'selected': selected_value}

@app.callback(
    Output('dropdown-2', 'options'),
    Input('intermediate-value', 'data')
)
def update_dropdown_2(intermediate_value):
    if intermediate_value['selected'] == 'A':
        return [{'label': i, 'value': i} for i in ['X', 'Y']]
    elif intermediate_value['selected'] == 'B':
        return [{'label': i, 'value': i} for i in ['Y', 'Z']]
    else:
        return []

if __name__ == '__main__':
    app.run_server(debug=True)

options_1 = [{'label': i, 'value': i} for i in ['A', 'B', 'C']]
options_2 = [{'label': i, 'value': i} for i in ['X', 'Y', 'Z']]

app.layout = html.Div([
    dcc.Dropdown(
        id='dropdown-1',
        options=options_1,
        value='A'
    ),
    dcc.Dropdown(
        id='dropdown-2',
        options=options_2,
        value=None
    )
])

/* 示例CSS样式 */
.dropdown {
    margin: 10px;
}

app.layout = html.Div([
    dcc.Dropdown(
        id='dropdown-1',
        options=[{'label': i, 'value': i} for i in ['A', 'B', 'C']],
        value='A',
        className='dropdown'
    ),
    dcc.Dropdown(
        id='dropdown-2',
        options=[],
        value=None,
        className='dropdown'
    )
])