fix: documents in graphql-config can be null (#518)

Author: Dimitri POSTOLOV

.changeset/proud-bikes-tease.md

@@ -0,0 +1,5 @@
+---
+'@graphql-eslint/eslint-plugin': patch
+---
+
+fix: documents in graphql-config can be null

packages/plugin/src/sibling-operations.ts

@@ -70,7 +70,7 @@ export function getSiblingOperations(options: ParserOptions, gqlConfig: GraphQLC
     } else {
       const projectForFile = gqlConfig.getProjectForFile(options.filePath);
 
-      if (projectForFile && projectForFile.documents.length > 0) {
+      if (projectForFile?.documents) {
         siblings = projectForFile.loadDocumentsSync(projectForFile.documents, {
           skipGraphQLImport: true,
         });