sync knex & DB transaction state on trx callback error throw

Previously throwing an error directly from a transaction callback
resulted in knex reporting that transaction's promise as rejected, and
releasing used connection (back to the connection pool), but not
telling the database to roll back that connection's transaction.

src/transaction.js

@@ -32,10 +32,15 @@ function Transaction(client, container, config, outerTx) {
       return makeTransactor(this, connection, trxClient)
     })
     .then((transactor) => {
-      var result = container(transactor)
-
       // If we've returned a "thenable" from the transaction container, assume
       // the rollback and commit are chained to this object's success / failure.
+      // Directly thrown errors are treated as automatic rollbacks.
+      var result
+      try {
+        result = container(transactor)
+      } catch (err) {
+        result = Promise.reject(err)
+      }
       if (result && result.then && typeof result.then === 'function') {
         result.then((val) => {
           transactor.commit(val)