fix(flushMicroTasks): Fallback to no scheduler in case of exception

Closes testing-library#736

src/flush-microtasks.js

@@ -20,7 +20,7 @@ function getIsUsingFakeTimers() {
 
 const globalObj = typeof window === 'undefined' ? global : window
 let Scheduler = globalObj.Scheduler
-const isModernScheduleCallbackSupported = satisfies(React.version, '>16.8.6', {
+let isModernScheduleCallbackSupported = satisfies(React.version, '>16.8.6', {
   includePrerelease: true,
 })
 
@@ -58,6 +58,17 @@ try {
           'if you encounter this warning.',
       )
     }
+
+    if (isModernScheduleCallbackSupported) {
+      // eslint-disable-next-line no-console
+      console.error(
+        'This environment does not support module requiring, so we cannot require the Scheduler. ' +
+          'To fix this you can require the Scheduler in your test setup file.',
+      )
+
+      // Fallback to no scheduleCallback Supported.
+      isModernScheduleCallbackSupported = false
+    }
   }
 }