diff --git a/json/src/com/jetbrains/jsonSchema/JsonSchemaVfsListener.java b/json/src/com/jetbrains/jsonSchema/JsonSchemaVfsListener.java
index b82b0060be21..756a22d3ec04 100644
--- a/json/src/com/jetbrains/jsonSchema/JsonSchemaVfsListener.java
+++ b/json/src/com/jetbrains/jsonSchema/JsonSchemaVfsListener.java
@@ -8,7 +8,6 @@ import com.intellij.openapi.application.ReadAction;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.editor.EditorFactory;
 import com.intellij.openapi.editor.ex.EditorEx;
-import com.intellij.openapi.project.DumbService;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.ZipperUpdater;
 import com.intellij.openapi.vfs.VirtualFile;
@@ -72,7 +71,6 @@ public class JsonSchemaVfsListener extends BulkVirtualFileListenerAdapter {
       myUpdater = new ZipperUpdater(200, Alarm.ThreadToUse.POOLED_THREAD, project);
       myService = service;
       myRunnable = () -> {
-        if (DumbService.isDumb(project)) return;
         Collection<VirtualFile> scope = new HashSet<>(myDirtySchemas);
         myDirtySchemas.removeAll(scope);
 
diff --git a/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaFileValuesIndex.java b/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaFileValuesIndex.java
index 15586a5ed496..49457b857c2a 100644
--- a/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaFileValuesIndex.java
+++ b/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaFileValuesIndex.java
@@ -4,6 +4,7 @@ package com.jetbrains.jsonSchema.impl;
 import com.intellij.json.JsonFileType;
 import com.intellij.json.json5.Json5FileType;
 import com.intellij.json.psi.JsonFile;
+import com.intellij.openapi.project.DumbService;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.PsiFile;
@@ -41,7 +42,7 @@ public class JsonSchemaFileValuesIndex extends FileBasedIndexExtension<String, S
       @NotNull
       public Map<String, String> map(@NotNull FileContent inputData) {
         PsiFile file = inputData.getPsiFile();
-        assert file instanceof JsonFile;
+        if (!(file instanceof JsonFile)) return ContainerUtil.newHashMap();
         HashMap<String, String> map = ContainerUtil.newHashMap();
         String schemaUrl = JsonCachedValues.fetchSchemaUrl(file);
         map.put(JsonCachedValues.URL_CACHE_KEY, schemaUrl == null ? NULL : schemaUrl);
@@ -97,7 +98,7 @@ public class JsonSchemaFileValuesIndex extends FileBasedIndexExtension<String, S
 
   @Nullable
   public static String getCachedValue(Project project, VirtualFile file, String requestedKey) {
-    if (project.isDisposed() || !file.isValid()) return null;
+    if (project.isDisposed() || !file.isValid() || DumbService.isDumb(project)) return NULL;
     Collection<String> keys = FileBasedIndex.getInstance().getAllKeys(INDEX_ID, project);
     for (String key: keys) {
       if (requestedKey.equals(key)) {