Fix for difficulty adjustment throwing error before in sync

backend/src/api/bitcoin/bitcoin.routes.ts

@@ -510,7 +510,12 @@ class BitcoinRoutes {
 
   private getDifficultyChange(req: Request, res: Response) {
     try {
-      res.json(difficultyAdjustment.getDifficultyAdjustment());
+      const da = difficultyAdjustment.getDifficultyAdjustment();
+      if (da) {
+        res.json(da);
+      } else {
+        res.status(503).send(`Service Temporarily Unavailable`);
+      }
     } catch (e) {
       res.status(500).send(e instanceof Error ? e.message : e);
     }

backend/src/api/difficulty-adjustment.ts

@@ -81,14 +81,15 @@ export function calcDifficultyAdjustment(
 }
 
 class DifficultyAdjustmentApi {
-  constructor() { }
-
-  public getDifficultyAdjustment(): IDifficultyAdjustment {
+  public getDifficultyAdjustment(): IDifficultyAdjustment | null {
     const DATime = blocks.getLastDifficultyAdjustmentTime();
     const previousRetarget = blocks.getPreviousDifficultyRetarget();
     const blockHeight = blocks.getCurrentBlockHeight();
     const blocksCache = blocks.getBlocks();
     const latestBlock = blocksCache[blocksCache.length - 1];
+    if (!latestBlock) {
+      return null;
+    }
     const nowSeconds = Math.floor(new Date().getTime() / 1000);
 
     return calcDifficultyAdjustment(