add cast

Author: AbhiPrasad

packages/core/src/transports/base.ts

@@ -107,7 +107,7 @@ export function createTransport(
   const flush = (timeout?: number): PromiseLike<boolean> => buffer.drain(timeout);
 
   function send(envelope: Envelope): PromiseLike<TransportResponse> {
-    const category = getEnvelopeType(envelope);
+    const category = getEnvelopeType(envelope) as TransportCategory;
     const request: TransportRequest = {
       category,
       body: serializeEnvelope(envelope),