Throw error where most recent fetched signature has slot less than afterSlot

src/index.ts

@@ -228,8 +228,8 @@ async function main() {
     } catch (e: any) {
       notify('v3: ' + e.toString());
       console.log(e, e.stack);
-      // Wait for 10 mins
-      await sleep(10 * 60 * 1000);
+      // Wait for 60 seconds
+      await sleep(60 * 1000);
     }
   }
 }

src/signatures.ts

@@ -32,6 +32,11 @@ export async function getNewSignatures(
     signatures = signaturesInfo.map((x) => x['signature']);
     slots = signaturesInfo.map((x) => x['slot']);
 
+    if (signaturesInfo[0].slot < afterSlot) {
+      // Possibly this happens when validators are switched at the endpoint?
+      throw 'most recent fetched signature has slot less than afterSlot'
+    }
+
     console.log('slots ' + signaturesInfo[0].slot + ' to ' + signaturesInfo[signaturesInfo.length - 1].slot)
     console.log(
       new Date(