requested idx == nil fix; add doc comment

disco/disco.go

@@ -312,6 +312,8 @@ type inMemSchemator struct {
 	schema Schema
 }
 
+// NewInMemSchemator instantiates an InMemSchemator
+// this allows new holders to have thier own, and not rely on a shared instance
 func NewInMemSchemator() *inMemSchemator {
 	return &inMemSchemator{
 		schema: make(Schema),

index.go

@@ -267,40 +267,42 @@ func (i *Index) openFields(idx *disco.Index) error {
 	eg, ctx := errgroup.WithContext(context.Background())
 	var mu sync.Mutex
 
-	if idx != nil {
-	fileLoop:
-		for fname, fld := range idx.Fields {
-			select {
-			case <-ctx.Done():
-				break fileLoop
-			default:
-				var cfm *CreateFieldMessage = &CreateFieldMessage{}
-				var err error
+	if idx == nil {
+		return nil
+	}
+fileLoop:
+	for fname, fld := range idx.Fields {
+		select {
+		case <-ctx.Done():
+			break fileLoop
+		default:
+			var cfm *CreateFieldMessage = &CreateFieldMessage{}
+			var err error
 
-				// Decode the CreateFieldMessage from the schema data in order to
-				// get its metadata.
-				cfm, err = decodeCreateFieldMessage(i.holder.serializer, fld.Data)
+			// Decode the CreateFieldMessage from the schema data in order to
+			// get its metadata.
+			cfm, err = decodeCreateFieldMessage(i.holder.serializer, fld.Data)
+			if err != nil {
+				return errors.Wrap(err, "decoding create field message")
+			}
+
+			indexQueue <- struct{}{}
+			eg.Go(func() error {
+				defer func() {
+					<-indexQueue
+				}()
+				i.holder.Logger.Debugf("open field: %s", fname)
+
+				_, err := i.openField(&mu, cfm, fname)
 				if err != nil {
-					return errors.Wrap(err, "decoding create field message")
+					return errors.Wrap(err, "opening field")
 				}
 
-				indexQueue <- struct{}{}
-				eg.Go(func() error {
-					defer func() {
-						<-indexQueue
-					}()
-					i.holder.Logger.Debugf("open field: %s", fname)
-
-					_, err := i.openField(&mu, cfm, fname)
-					if err != nil {
-						return errors.Wrap(err, "opening field")
-					}
-
-					return nil
-				})
-			}
+				return nil
+			})
 		}
 	}
+
 	err = eg.Wait()
 	if err != nil {
 		// Close any fields which got opened, since the overall