IDE: IndexNotReadyException while creating new Kotlin file in Dumb mode

^KT-42518

idea/idea-jvm/src/org/jetbrains/kotlin/idea/configuration/ConfigureKotlinInProjectUtils.kt

@@ -10,6 +10,7 @@ import com.intellij.openapi.command.WriteCommandAction
 import com.intellij.openapi.diagnostic.Logger
 import com.intellij.openapi.extensions.Extensions
 import com.intellij.openapi.module.Module
+import com.intellij.openapi.project.DumbService
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.projectRoots.JavaSdkVersion
 import com.intellij.openapi.roots.DependencyScope
@@ -27,6 +28,7 @@ import org.jetbrains.annotations.CalledInBackground
 import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.idea.KotlinJvmBundle
+import org.jetbrains.kotlin.idea.actions.internal.refactoringTesting.readAction
 import org.jetbrains.kotlin.idea.core.util.getKotlinJvmRuntimeMarkerClass
 import org.jetbrains.kotlin.idea.framework.JSLibraryKind
 import org.jetbrains.kotlin.idea.framework.effectiveKind
@@ -162,10 +164,19 @@ fun getConfigurableModulesWithKotlinFiles(project: Project): List<ModuleSourceRo
 }
 
 fun showConfigureKotlinNotificationIfNeeded(module: Module) {
-    val moduleGroup = module.toModuleGroup()
-    if (!isNotConfiguredNotificationRequired(moduleGroup)) return
+    val action: () -> Unit = {
+        val moduleGroup = module.toModuleGroup()
+        if (isNotConfiguredNotificationRequired(moduleGroup)) {
+            ConfigureKotlinNotificationManager.notify(module.project)
+        }
+    }
 
-    ConfigureKotlinNotificationManager.notify(module.project)
+    val dumbService = DumbService.getInstance(module.project)
+    if (dumbService.isDumb) {
+        dumbService.smartInvokeLater { action() }
+    } else {
+        action()
+    }
 }
 
 fun isNotConfiguredNotificationRequired(moduleGroup: ModuleSourceRootGroup): Boolean {