fix: React next fails on build (#726)

src/flush-microtasks.js

@@ -1,3 +1,5 @@
+import scheduleCallback from './scheduler-compat'
+
 /* istanbul ignore file */
 // the part of this file that we need tested is definitely being run
 // and the part that is not cannot easily have useful tests written
@@ -17,6 +19,7 @@ function getIsUsingFakeTimers() {
 
 let didWarnAboutMessageChannel = false
 let enqueueTask
+
 try {
   // read require off the module object to get around the bundlers.
   // we don't want them to detect a require and bundle a Node polyfill.
@@ -59,7 +62,11 @@ export default function flushMicroTasks() {
         jest.advanceTimersByTime(0)
         resolve()
       } else {
-        enqueueTask(resolve)
+        scheduleCallback(null, () => {
+          enqueueTask(() => {
+            resolve()
+          })
+        })
       }
     },
   }

src/scheduler-compat.js

@@ -0,0 +1,76 @@
+const globalObj = typeof window === 'undefined' ? global : window
+
+let Scheduler = globalObj.Scheduler
+try {
+  const requireString = `require${Math.random()}`.slice(0, 7)
+  const nodeRequire = module && module[requireString]
+  // import React's scheduler so we'll be able to schedule our tasks later on.
+  Scheduler = nodeRequire.call(module, 'scheduler')
+} catch (_err) {
+  console.error("The react version you're using doesn't support Scheduling")
+}
+// in case this react version has a Scheduler implementation, we use it,
+// if not, we just create a function calling our callback
+const NormalPriority = Scheduler
+  ? Scheduler.NormalPriority || Scheduler.unstable_NormalPriority
+  : null
+
+const isScheduleCallbackSupported = Scheduler !== undefined
+let isModernScheduleCallbackSupported = null
+
+const errorHandler = e => {
+  // If the error originated from Scheduler, it means we're in v16.8.6
+  if (
+    e.message === 'callback is not a function' &&
+    e.filename.includes('scheduler')
+  ) {
+    console.error(e.error.stack, e.error.detail)
+    e.preventDefault()
+  } else {
+    console.error(e.error)
+  }
+}
+
+export default function scheduleCallback(_, cb) {
+  if (!isScheduleCallbackSupported) {
+    return cb()
+  }
+
+  if (isModernScheduleCallbackSupported === null) {
+    // patch console.error here
+    const originalConsoleError = console.error
+    console.error = function error(...args) {
+      /* if console.error fired *with that specific message* */
+      /* istanbul ignore next */
+      const firstArgIsString = typeof args[0] === 'string'
+      if (
+        firstArgIsString &&
+        args[0].indexOf('TypeError: callback is not a function') === 0
+      ) {
+        // v16.8.6
+        isModernScheduleCallbackSupported = false
+        globalObj.removeEventListener('error', errorHandler)
+        console.error = originalConsoleError
+        return cb()
+      } else {
+        originalConsoleError.apply(console, args)
+        console.error = originalConsoleError
+        return cb()
+      }
+    }
+
+    globalObj.addEventListener('error', errorHandler)
+    return Scheduler.unstable_scheduleCallback(NormalPriority, () => {
+      console.error = originalConsoleError
+      isModernScheduleCallbackSupported = true
+      globalObj.removeEventListener('error', errorHandler)
+      return cb()
+    })
+  } else if (isModernScheduleCallbackSupported === false) {
+    return cb()
+  }
+
+  return Scheduler.unstable_scheduleCallback(NormalPriority, cb)
+}
+
+/* eslint no-console:0 */