Can't configure a FlutterTestUtils with a fake SDK

I'm trying to write a test that uses a fake Flutter SDK instead of a real one.

To do this, I've tried using the FlutterModuleFixture with an option to fake out the SDK. This option exists on the FlutterTestUtils, but doesn't appear to be used anywhere in our test code. See https://github.com/DaveShuckerow/flutter-intellij/pull/new/run-mode for what I did.

java.lang.IllegalStateException: @NotNull method io/flutter/sdk/FlutterSdkManager.getInstance must not return null

at io.flutter.sdk.FlutterSdkManager.$$$reportNull$$$0(FlutterSdkManager.java)
at io.flutter.sdk.FlutterSdkManager.getInstance(FlutterSdkManager.java:34)
at io.flutter.sdk.FlutterSdkUtil.setFlutterSdkPath(FlutterSdkUtil.java:230)
at io.flutter.testing.FlutterTestUtils.lambda$configureFlutterSdk$0(FlutterTestUtils.java:51)
at com.intellij.openapi.application.impl.ApplicationImpl.runWriteAction(ApplicationImpl.java:1038)
at io.flutter.testing.FlutterTestUtils.configureFlutterSdk(FlutterTestUtils.java:50)
at io.flutter.testing.FlutterModuleFixture.lambda$before$1(FlutterModuleFixture.java:36)
at io.flutter.testing.Testing.lambda$runOnDispatchThread$7(Testing.java:103)
at com.intellij.openapi.application.TransactionGuardImpl.lambda$submitTransactionAndWait$2(TransactionGuardImpl.java:165)
at com.intellij.openapi.application.TransactionGuardImpl.runSyncTransaction(TransactionGuardImpl.java:88)
at com.intellij.openapi.application.TransactionGuardImpl.lambda$submitTransaction$1(TransactionGuardImpl.java:111)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.doRun(LaterInvocator.java:447)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.runNextEvent(LaterInvocator.java:431)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:415)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:817)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:758)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:394)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)