feat: enhance concurrency management by adding WaitGroup support in extractors and loaders

cmd/go_migrate/extractor-error-handler.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"sync"
 
 	"github.com/google/uuid"
 )
@@ -25,6 +26,7 @@ func extractorErrorHandler(
 	chErrorsIn <-chan ExtractorError,
 	chBatchesOut chan<- Batch,
 	chJobErrorsOut chan<- JobError,
+	wgActiveBatches *sync.WaitGroup,
 ) {
 	for {
 		if ctx.Err() != nil {
@@ -52,6 +54,8 @@ func extractorErrorHandler(
 				case <-ctx.Done():
 					return
 				}
+
+				wgActiveBatches.Done()
 				continue
 			}