Function warnOnInvalidKey

docs/index.js:23598–23627

(returnFiber, workInProgress, child, knownKeys)

        return null;
      }
      function warnOnInvalidKey(returnFiber, workInProgress, child, knownKeys) {
        if ("object" !== typeof child || null === child) return knownKeys;
        switch (child.$$typeof) {
          case REACT_ELEMENT_TYPE:
          case REACT_PORTAL_TYPE:
            warnForMissingKey(returnFiber, workInProgress, child);
            var key = child.key;
            if ("string" !== typeof key) break;
            if (null === knownKeys) {
              knownKeys = new Set();
              knownKeys.add(key);
              break;
            }
            if (!knownKeys.has(key)) {
              knownKeys.add(key);
              break;
            }
            runWithFiberInDEV(workInProgress, function () {
              console.error(
                "Encountered two children with the same key, `%s`. Keys should be unique so that components maintain their identity across updates. Non-unique keys may cause children to be duplicated and/or omitted \u2014 the behavior is unsupported and could change in a future version.",
                key
              );
            });
            break;
          case REACT_LAZY_TYPE:
            (child = callLazyInitInDEV(child)),
              warnOnInvalidKey(returnFiber, workInProgress, child, knownKeys);
        }
        return knownKeys;
      }
      function reconcileChildrenArray(
        returnFiber,
        currentFirstChild,