Make block index calls optional

crates/apps_lib/src/client/masp.rs

@@ -110,7 +110,7 @@ pub async fn syncing<
             ))
         })?;
 
-        dispatch_client!(IndexerMaspClient::new(client, url))?
+        dispatch_client!(IndexerMaspClient::new(client, url, true))?
     } else {
         display_line!(
             io,

crates/sdk/src/masp/shielded_sync/utils.rs

@@ -453,11 +453,21 @@ impl RequestBuilderExt for reqwest::RequestBuilder {
 impl IndexerMaspClient {
     /// Create a new [`IndexerMaspClient`].
     #[inline]
-    pub fn new(client: reqwest::Client, indexer_api: reqwest::Url) -> Self {
+    pub fn new(
+        client: reqwest::Client,
+        indexer_api: reqwest::Url,
+        using_block_index: bool,
+    ) -> Self {
         let shared = Arc::new(IndexerMaspClientShared {
             indexer_api,
             semaphore: Semaphore::new(MAX_CONCURRENT_REQUESTS),
-            block_index: init_once::InitOnce::new(),
+            block_index: {
+                let index = init_once::InitOnce::new();
+                if !using_block_index {
+                    debug_assert!(index.try_init(|| None).is_some());
+                }
+                index
+            },
         });
         Self { client, shared }
     }