ApplicationInsights-node.js: Receiving "Zone already loaded" error when requiring AI client in Function App

Using applicationinsights@1.0.0 I am receiving this error, which causes the function to fail and respond 500:

2017-10-25T14:58:03.588 Exception while executing function: Functions.di-session-update
2017-10-25T14:58:03.588 Error: Zone already loaded.
    at new Error (native)
    at D:\home\site\wwwroot\node_modules\zone.js\dist\zone-node.js:25:15 [<root>]
    at D:\home\site\wwwroot\node_modules\zone.js\dist\zone-node.js:971:3 [<root>]
    at Zone.Zone.zoneSpec._properties (D:\home\site\wwwroot\node_modules\zone.js\dist\zone-node.js:9:68)
    at Object.<anonymous> (D:\home\site\wwwroot\node_modules\zone.js\dist\zone-node.js:12:2)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.require (module.js:497:17)
    at Module.patchedRequire [as require] (D:\home\site\wwwroot\node_modules\diagnostic-channel\dist\src\patchRequire.js:14:46)
    at require (internal/module.js:20:19)
2017-10-25T14:58:03.588 Function completed (Failure, Id=9b458b5a-010e-4bbf-adaa-3616ea3de4b7, Duration=28ms)
2017-10-25T14:58:03.588 Executed 'Functions.di-session-update' (Failed, Id=9b458b5a-010e-4bbf-adaa-3616ea3de4b7)

This isn’t an issue for my other function which is part of the function app.

My functions currently share a package.json file between them, and I configure the ApplicationInsights client inside some shared library code, so I wonder if there’s something happening here which might cause the module to be included twice:

const appInsights = require('applicationinsights');
function setupInsights() {
    /* omitted dev-only code which skips setup if process.env.NODE_ENV is dev */
    appInsights.setup()
        .setAutoCollectConsole(true, true) // Enable logging of all console methods.
        .start();
    return appInsights;
}

module.exports = setupInsights();

I had a look in CorrelationContextManager.js to see where it’s being required, but I’m not doing anything too special.