function addGlobalUnhandledRejectionInstrumentationHandler(
  handler,
) {
  const type = 'unhandledrejection';
  _handlers.addHandler(type, handler);
  _handlers.maybeInstrument(type, instrumentUnhandledRejection);
}
Add an instrumentation handler for when an unhandled promise rejection is captured.

Use at your own risk, this might break without changelog notice, only used internally.
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