[bugfix] more nil checks baybeeeeeeeeeeeeeeeeeeee (#854)

* more nil checks baybeeeeeeeeeeeeeeeeeeee

Signed-off-by: kim <grufwub@gmail.com>

* move item nil checks

Signed-off-by: kim <grufwub@gmail.com>

Signed-off-by: kim <grufwub@gmail.com>

internal/federation/dereferencing/thread.go

@@ -152,8 +152,6 @@ type frame struct {
 		statusable ap.Statusable
 		page       ap.CollectionPageable
 		itemIter   vocab.ActivityStreamsItemsPropertyIterator
-		iterLen    int
-		iterIdx    int
 	}
 
 	var (
@@ -240,22 +238,22 @@ type frame struct {
 					continue stackLoop
 				}
 
-				// Check this page contains any items...
-				if current.iterLen = items.Len(); current.iterLen == 0 {
-					continue stackLoop
-				}
-
 				// Start off the item iterator
 				current.itemIter = items.Begin()
-				current.iterIdx = 0
+				if current.itemIter == nil {
+					continue stackLoop
+				}
 			}
 
 		itemLoop:
-			for ; current.iterIdx < current.iterLen; current.iterIdx++ {
+			for {
 				var itemIRI *url.URL
 
 				// Get next item iterator object
 				current.itemIter = current.itemIter.Next()
+				if current.itemIter == nil {
+					break itemLoop
+				}
 
 				if iri := current.itemIter.GetIRI(); iri != nil {
 					// Item is already an IRI type
@@ -284,13 +282,6 @@ type frame struct {
 					continue itemLoop
 				}
 
-				// Iter past this item. Normally this would be
-				// handled by the third clause of the itemLoop's
-				// embedded range checking, but at the bottom of this
-				// loop since we found a new status we circle back to
-				// the beginning of the stackLoop and skip iteration.
-				current.iterIdx++
-
 				// Put current and next frame at top of stack
 				stack = append(stack, current, &frame{
 					statusIRI:  itemIRI,
@@ -301,9 +292,6 @@ type frame struct {
 				continue stackLoop
 			}
 
-			// Item iterator is done
-			current.itemIter = nil
-
 			// Get the current page's "next" property
 			pageNext := current.page.GetActivityStreamsNext()
 			if pageNext == nil {