Function warnForMissingKey

packages/react-server/src/ReactFlightServer.js:1773–1837

(
  request: Request,
  key: null | string,
  componentDebugInfo: ReactComponentInfo,
  debugTask: null | ConsoleTask,
)

}

function warnForMissingKey(
  request: Request,
  key: null | string,
  componentDebugInfo: ReactComponentInfo,
  debugTask: null | ConsoleTask,
): void {
  if (__DEV__) {
    let didWarnForKey = request.didWarnForKey;
    if (didWarnForKey == null) {
      didWarnForKey = request.didWarnForKey = new WeakSet();
    }
    const parentOwner = componentDebugInfo.owner;
    if (parentOwner != null) {
      if (didWarnForKey.has(parentOwner)) {
        // We already warned for other children in this parent.
        return;
      }
      didWarnForKey.add(parentOwner);
    }

    // Call with the server component as the currently rendering component
    // for context.
    const logKeyError = () => {
      console.error(
        'Each child in a list should have a unique "key" prop.' +
          '%s%s See https://react.dev/link/warning-keys for more information.',
        '',
        '',
      );
    };

    if (supportsComponentStorage) {
      // Run the component in an Async Context that tracks the current owner.
      if (debugTask) {
        debugTask.run(
          // $FlowFixMe[method-unbinding]
          componentStorage.run.bind(
            componentStorage,
            componentDebugInfo,
            callComponentInDEV,
            logKeyError,
            null,
            componentDebugInfo,
          ),
        );
      } else {
        componentStorage.run(
          componentDebugInfo,
          callComponentInDEV,
          logKeyError,
          null,
          componentDebugInfo,
        );
      }
    } else {
      if (debugTask) {
        debugTask.run(
          callComponentInDEV.bind(null, logKeyError, null, componentDebugInfo),