Decouple XHR instrumentation from breadcrumbs

[lobsterkatie]

For many types of events, the code to capture them as breadcrumbs is separate from the code to capture any time they error. (For example, addEventListener is wrapped for breadcrumb purposes here, and for exception-catching purposes here. The key difference is the use of wrap in the latter but not the former.) This lets the two types of capturing be turned on or off independently.

For XHR requests, however, we do both in the same spot (for instance here - you can see that we're using wrap even though we're in breadcrumbs.ts, not trycatch.ts). This means there's no way to turn off the capturing of XHR request errors without also turning off XHR breadcrumbs.

Can we fix this for the next major version?

[lobsterkatie]

For anyone happening upon this and wanting to turn off all automatic error reporting but not XHR breadcrumbs, until this is fixed you can do the following:

Sentry.init({
  dsn: "YOUR DSN HERE",

  // this turns off all automatic error reporting *except for XHR errors*
  integrations: integrations => {
    // integrations will be all default integrations
    return integrations.filter(function(integration) {
      const name = integration.name;
      return name !== "GlobalHandlers" && name !== "TryCatch";
    });
  },

  // this blocks all remaining automatically-caught errors (XHR errors)
  // this is the workaround given the above issue
  beforeSend: (event, hint) => {
    // try just so as to avoid having to assert each step of the chain
    try {
      if (event.exception.values[0].mechanism.type === "instrument") {
        return null;
      }
    } catch (oO) {}

    return event;
  }
});