Three points from discussion in https://github.com/reactjs/react-redux/issues/756:

* Due to https://bugs.chromium.org/p/chromium/issues/detail?id=701371, environments like CodeSandbox show `Error: null` in our “React caught an error” warning. Let’s consider skipping both as they’re not very useful and look like a bug. `Error: null` looks like a separate error and draws attention away from the real error just above.

* In any case we should probably not print `The error was thrown at:` if we don’t have a JS stack.

* There is a related issue. What do we pass to error boundary if we caught `null`? It seems that most error boundaries will intuitively do something like `if (this.state.error)` or read `error.message`, which `null` will break. There are other falsy values too like `''` and `undefined`. My proposal is we always wrap primitives into our own `Error` objects that we pass to the boundary.
node = node.return;
    }
  }
  function getPriorityContext(
    fiber: Fiber,
    forceAsync: boolean,
  ): PriorityLevel {
    let priorityLevel = priorityContext;
    if (priorityLevel === NoWork) {
      if (
        !useSyncScheduling ||
        fiber.internalContextTag & AsyncUpdates ||
        forceAsync
      ) {
        priorityLevel = LowPriority;
      } else {
        priorityLevel = SynchronousPriority;
      }
    }
     
     
    if (
      priorityLevel === SynchronousPriority &&
      (isPerformingWork || isBatchingUpdates)
    ) {
      return TaskPriority;
    }
    return priorityLevel;
  }
  function scheduleErrorRecovery(fiber: Fiber) {