Fix migration script error handling and improve documentation

- Add proper error handling for JSON marshaling in bulk update processing
- Fix scroll timeout format to use duration string instead of minutes
- Add links to PR #20 and query service repository in documentation
- Simplify usage examples to use go run directly instead of building
- Remove redundant custom configuration section from README

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Signed-off-by: Andres Tobon <[email protected]>

Author: andrest50

scripts/migration/001_add_access_query_fields/README.md

@@ -1,39 +1,26 @@
 # Access Query Fields Migration Script
 
-This script migrates existing OpenSearch documents to add the new `access_check_query` and `history_check_query` fields that were recently added to the enricher system.
+This script migrates existing OpenSearch documents to add the new `access_check_query` and `history_check_query` fields that were recently added as part of [PR #20](https://github.com/linuxfoundation/lfx-v2-indexer-service/pull/20).
 
 ## Background
 
-The LFX indexer service was recently updated to include new query fields for Fine-Grained Authorization (FGA):
+The LFX indexer service was recently updated to include new document fields for Fine-Grained Authorization (FGA) of documents via the [query service](https://github.com/linuxfoundation/lfx-v2-query-service):
 
 - `access_check_query`: Combination of `access_check_object` + "#" + `access_check_relation`
 - `history_check_query`: Combination of `history_check_object` + "#" + `history_check_relation`
 
-These fields are automatically populated for newly indexed documents, but existing documents need to be migrated.
+These fields are automatically populated for newly indexed documents (implemented in [PR #20](https://github.com/linuxfoundation/lfx-v2-indexer-service/pull/20)), but existing documents need to be migrated.
 
 ## Usage
 
 ### Basic Usage
 
 ```bash
-# Build the migration script
-go build -o migrate main.go
-
 # Run in dry-run mode to see what would be changed
-DRY_RUN=true ./migrate
+DRY_RUN=true go run scripts/migration/001_add_access_query_fields/main.go
 
 # Run the actual migration
-./migrate
-```
-
-### With Custom Configuration
-
-```bash
-# Custom OpenSearch settings
-OPENSEARCH_URL=http://opensearch:9200 \
-OPENSEARCH_INDEX=resources \
-BATCH_SIZE=500 \
-./migrate
+go run scripts/migration/001_add_access_query_fields/main.go
 ```
 
 ## Environment Variables
@@ -71,7 +58,7 @@ The script:
 
 ## Example Output
 
-```
+```text
 Starting access query fields migration...
 === Migration Configuration ===
   OpenSearch URL: http://opensearch:9200

scripts/migration/001_add_access_query_fields/main.go

@@ -10,7 +10,7 @@
 //
 // Usage:
 //
-//	go run scripts/data-migration/add-access-query-fields/main.go
+//	go run scripts/migration/001_add_access_query_fields/main.go
 //
 // Environment variables:
 //   - OPENSEARCH_URL: OpenSearch cluster URL (default: http://localhost:9200)
@@ -116,7 +116,6 @@ func loadConfig() *Config {
 	return config
 }
 
-
 // createOpenSearchClient creates and configures OpenSearch client
 func createOpenSearchClient(config *Config) (*opensearch.Client, error) {
 	cfg := opensearch.Config{
@@ -247,7 +246,7 @@ func searchDocuments(ctx context.Context, client *opensearch.Client, config *Con
 func scrollDocuments(ctx context.Context, client *opensearch.Client, scrollID string, scrollTimeout time.Duration) (*SearchResponse, error) {
 	scrollBody := map[string]interface{}{
 		"scroll_id": scrollID,
-		"scroll":    fmt.Sprintf("%dm", int(scrollTimeout.Minutes())),
+		"scroll":    scrollTimeout.String(),
 	}
 
 	scrollBodyJSON, err := json.Marshal(scrollBody)
@@ -328,7 +327,11 @@ func processBatch(ctx context.Context, client *opensearch.Client, config *Config
 		bulkBody.WriteString(fmt.Sprintf(`{"update":{"_index":"%s","_id":"%s"}}`, config.IndexName, doc.ID))
 		bulkBody.WriteString("\n")
 
-		updateJSON, _ := json.Marshal(map[string]interface{}{"doc": updateDoc})
+		updateJSON, err := json.Marshal(map[string]interface{}{"doc": updateDoc})
+		if err != nil {
+			stats.ErroredDocuments++
+			return fmt.Errorf("failed to marshal update document for %s: %w", doc.ID, err)
+		}
 		bulkBody.Write(updateJSON)
 		bulkBody.WriteString("\n")