Function handleThrow

packages/react-reconciler/src/ReactFiberWorkLoop.js:2211–2339

(root: FiberRoot, thrownValue: any)

}

function handleThrow(root: FiberRoot, thrownValue: any): void {
  // A component threw an exception. Usually this is because it suspended, but
  // it also includes regular program errors.
  //
  // We're either going to unwind the stack to show a Suspense or error
  // boundary, or we're going to replay the component again. Like after a
  // promise resolves.
  //
  // Until we decide whether we're going to unwind or replay, we should preserve
  // the current state of the work loop without resetting anything.
  //
  // If we do decide to unwind the stack, module-level variables will be reset
  // in resetSuspendedWorkLoopOnUnwind.

  // These should be reset immediately because they're only supposed to be set
  // when React is executing user code.
  resetHooksAfterThrow();
  if (__DEV__) {
    resetCurrentFiber();
  }

  if (
    thrownValue === SuspenseException ||
    thrownValue === SuspenseActionException
  ) {
    // This is a special type of exception used for Suspense. For historical
    // reasons, the rest of the Suspense implementation expects the thrown value
    // to be a thenable, because before `use` existed that was the (unstable)
    // API for suspending. This implementation detail can change later, once we
    // deprecate the old API in favor of `use`.
    thrownValue = getSuspendedThenable();
    // TODO: Suspending the work loop during the render phase is
    // currently not compatible with sibling prerendering. We will add
    // this optimization back in a later step.
    // Don't suspend work loop, except to check if the data has
    // immediately resolved (i.e. in a microtask). Otherwise, trigger the
    // nearest Suspense fallback.
    workInProgressSuspendedReason = SuspendedOnImmediate;
  } else if (thrownValue === SuspenseyCommitException) {
    thrownValue = getSuspendedThenable();
    workInProgressSuspendedReason = SuspendedOnInstance;
  } else if (thrownValue === SelectiveHydrationException) {
    // An update flowed into a dehydrated boundary. Before we can apply the
    // update, we need to finish hydrating. Interrupt the work-in-progress
    // render so we can restart at the hydration lane.
    //
    // The ideal implementation would be able to switch contexts without
    // unwinding the current stack.
    //
    // We could name this something more general but as of now it's the only
    // case where we think this should happen.
    workInProgressSuspendedReason = SuspendedOnHydration;
  } else {
    // This is a regular error.
    const isWakeable =
      thrownValue !== null &&
      typeof thrownValue === 'object' &&
      typeof thrownValue.then === 'function';