fix: dag-scope=block also returns root block of last path segment

gateway/blocks_gateway.go

@@ -284,13 +284,17 @@ func walkGatewaySimpleSelector(ctx context.Context, p ipfspath.Path, params CarP
 	}
 
 	// If we just need to resolve the path then we're done
-	if params.Scope == dagScopeBlock {
-		return nil
-	}
+
+	// If the scope is the block, now we only need to retrieve the root block of the last element of the path.
 
 	lctx := ipld.LinkContext{Ctx: ctx}
 	pathTerminalCidLink := cidlink.Link{Cid: lastCid}
 
+	if params.Scope == dagScopeBlock {
+		_, err = lsys.LoadRaw(lctx, pathTerminalCidLink)
+		return err
+	}
+
 	// If we're asking for everything then give it
 	if params.Scope == dagScopeAll {
 		lastCidNode, err := lsys.Load(lctx, pathTerminalCidLink, basicnode.Prototype.Any)