[isomorphic-core] don't try and inflate delete deltas

Summary:
If we inflate delete deltas, the object we're trying to find won't exist
anymore (we just deleted it!). This is likely causing the `While inflating
${sourceName} transactions, we couldn't find models for some ${modelName}
IDs` error.

Fixes T7436

Test Plan: manual

Reviewers: spang, juan, halla

Reviewed By: halla

Maniphest Tasks: T7436

Differential Revision: https://phab.nylas.com/D3621

packages/isomorphic-core/src/delta-stream-builder.js

@@ -10,7 +10,10 @@ const stream = require('stream');
  * the inflated model they reference.
  */
 function inflateTransactions(db, accountId, transactions = [], sourceName) {
-  const transactionJSONs = transactions.map((t) => (t.toJSON ? t.toJSON() : t))
+  const transactionJSONs = transactions
+  .filter((t) => t.event !== 'delete')
+  .map((t) => (t.toJSON ? t.toJSON() : t))
+
   transactionJSONs.forEach((t) => {
     t.cursor = t.id;
     t.accountId = accountId;