fix: fixes InvalidSignature errors that could happen during streaming

Author: gdorsi

packages/cojson/src/storage/storageAsync.ts

@@ -298,6 +298,10 @@ export class StorageApiAsync implements StorageAPI {
 
     const actuallyNewTransactions = newTransactions.slice(actuallyNewOffset);
 
+    if (actuallyNewTransactions.length === 0) {
+      return sessionRow?.lastIdx || 0;
+    }
+
     let newBytesSinceLastSignature =
       (sessionRow?.bytesSinceLastSignature || 0) +
       actuallyNewTransactions.reduce(

packages/cojson/src/storage/storageSync.ts

@@ -279,6 +279,10 @@ export class StorageApiSync implements StorageAPI {
 
     const actuallyNewTransactions = newTransactions.slice(actuallyNewOffset);
 
+    if (actuallyNewTransactions.length === 0) {
+      return sessionRow?.lastIdx || 0;
+    }
+
     let newBytesSinceLastSignature =
       (sessionRow?.bytesSinceLastSignature || 0) +
       actuallyNewTransactions.reduce(

packages/cojson/src/storage/syncUtils.ts

@@ -23,17 +23,17 @@ export function collectNewTxs({
   if (!sessionEntry) {
     sessionEntry = {
       after: firstNewTxIdx,
-      lastSignature: "WILL_BE_REPLACED" as Signature,
+      lastSignature: signature,
       newTransactions: [],
     };
     contentMessage.new[sessionRow.sessionID] = sessionEntry;
+  } else {
+    sessionEntry.lastSignature = signature;
   }
 
   for (const tx of newTxsInSession) {
     sessionEntry.newTransactions.push(tx.tx);
   }
-
-  sessionEntry.lastSignature = signature;
 }
 
 export function getDependedOnCoValues(