Demonstration that Strava Route Builder can't find routes at the prime meridian

stravaBug.js

// Open https://www.strava.com/routes/new, then copy/paste this code in the debug console.
// It should print results like this, showing that it can't find routes at the prime meridian:
//
// lng: -1.0, errCount: 0
// lng: -0.9, errCount: 0
// lng: -0.8, errCount: 1
// lng: -0.7, errCount: 0
// lng: -0.6, errCount: 0
// lng: -0.5, errCount: 0
// lng: -0.4, errCount: 0
// lng: -0.3, errCount: 0
// lng: -0.2, errCount: 0
// lng: -0.1, errCount: 0
// lng:  0  , errCount: 17       <----- HERE'S YOUR PROBLEM
// lng:  0.1, errCount: 0
// lng:  0.2, errCount: 0
// lng:  0.3, errCount: 0
// lng:  0.4, errCount: 0
// lng:  0.5, errCount: 0
// lng:  0.6, errCount: 0
// lng:  0.7, errCount: 0
// lng:  0.8, errCount: 0
// lng:  0.9, errCount: 1
// lng:  1.0, errCount: 0

function routeBetweenPoints(a, b) {
  return fetch('https://www.strava.com/routemaster/route', {
    method: "POST",
    headers: {
      'Content-Type': 'application/json; charset=utf-8',
      'X-CSRF-Token': document.getElementsByName('csrf-token')[0].getAttribute('content')
    },
    body: JSON.stringify({
      elements: [
        { element_type:1, waypoint: { point: a } },
        { element_type:1, waypoint: { point: b } }
      ],
      preferences: {
        popularity: 1,
        elevation: 0,
        route_type: 1,
        straight_line: false
      }
    })
  }).then(response => response.json());
}

function routeAtLatLng(lat, lng) {
  return routeBetweenPoints(
    { lat: lat, lng: lng-0.01 }, 
    { lat: lat, lng: lng+0.01 }
  );
}

function gen(from, to, by) {
  const xs = [];
  for (let x = from; x < to; x+=by) xs.push(x);
  return xs;
}

function errsAtLng(lng) {
  const lats = gen(44, 49, 0.2);
  return Promise.all(lats.map(lat => routeAtLatLng(lat, lng)))
    .then(routes => routes.filter(route => route.error === "Route request outside of routable paths"))
    .then(errs => errs.length);
}

const lngs = gen(-1, 1, 0.1);

Promise.all(lngs.map(lng =>
  errsAtLng(lng)
  .then(errCount => { return { lng: lng, errCount: errCount }; })
)).then(results => console.log(results));