Plotly – How do I plot a line on a map from a json file?

I’m trying to plot a line on a map in plotly from a json file and keep receiving the following error. All the examples on the plotly website use a .csv file. However, I’d like to use a json file. Any help would be greatly appreciated.

Error: No valid mapbox style found, please set mapbox.style to one of:
open-street-map, white-bg, carto-positron, carto-darkmatter, stamen-terrain, stamen-toner, stamen-watercolor
or register a Mapbox access token to use a Mapbox-served style.

Python:

import plotly.graph_objects as go
import pandas as pd
import json

with open('fcRailroad.geojson') as json_file:
    fcRailroad = json.load(json_file)

fig = go.Figure(go.Scattermapbox())

fig.update_layout(mapbox_style="stamen-terrain", 
                mapbox_zoom=10, 
                mapbox_center_lat = 40.58,
                mapbox_center_lon = -105.08,
                margin={"r":0,"t":0,"l":0,"b":0},
                mapbox=go.layout.Mapbox(
                    layers=[{
                        'sourcetype': 'geojson',
                        'source': fcRailroad,
                        'type': 'line',
                    }]
                ))

fig.show()

Json:

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "properties": {},
            "geometry": {
                "type": "LineString",
                "coordinates": [
                    [
                        -825.0913953781128,
                        40.49348616373978
                    ],
                    [
                        -825.0906443595885,
                        40.49508532104079
                    ],
                    [
                        -825.0863313674927,
                        40.502411585011934
                    ]
                ]
            }
        }
    ]
}