Callback on barchart/dropdown doesn't reset

Dash Python
1

I have this code which works well when it start, and when i select a different year. However when I select and then delete the year and want to go back to the default value which is ‘All Years’ (which works upon starting up),

I get an error: KeyError: (‘P04’, 1)

If someone can help me out id really appreciate it

app = dash.Dash()

app.css.append_css({
 "external_url": "https://codepen.io/chriddyp/pen/bWLwgP.css"
})


app.layout = html.Div([
html.H2("Encuesta Continua de Empleo Paraguay"),
html.Div([
    dcc.Dropdown(
            id="Manager",
            options=([{'label': year, 'value': year } for year in df['year'].unique()]),
            value='All Years',
            className='three columns' )
        ],),
# Empty
html.Div(className='twelve columns'),


html.Div(
    dcc.Graph(id='funnel-graph'),
        className='six columns')
])


@app.callback(
dash.dependencies.Output('funnel-graph', 'figure'),
[dash.dependencies.Input('Manager', 'value')])

def update_graph(year):
if year == "All Years":
    df_plot = df.copy()
    
else:
    df_plot = df[df['year'].isin([year])]
    

pv = pd.pivot_table(
    df_plot,
    index=['trimestre'],
    columns=["A15"],
    values=['P04'],
    aggfunc=len,
    fill_value=0)


trace1 = go.Bar(x=pv.index, y=pv[('P04',1)], name='Empleado / obrero público')
trace2 = go.Bar(x=pv.index, y=pv[('P04',2)], name='Empleado / obrero privado')
trace3 = go.Bar(x=pv.index, y=pv[('P04',3)], name='Empleador o patrón')
trace4 = go.Bar(x=pv.index, y=pv[('P04',4)], name='Trabajador por cuenta propia')
#trace5 = go.Bar(x=pv.index, y=pv[('P04',5)], name=4)
trace6 = go.Bar(x=pv.index, y=pv[('P04',6)], name='Empleado doméstico')

return {
    'data': [trace1, trace2, trace3, trace4, trace6],
    'layout':
    go.Layout(
        title='Categoría o posición que tenía en su última ocupación {}'.format(year),
        barmode='group')
}


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