fix: resolve TypeScript errors in merged code

- Add null check for decoded in getLIDsForPNs loop
- Fix jest mock typing in process-message.test.ts

src/Signal/lid-mapping.ts

@@ -522,7 +522,7 @@ export class LIDMappingStore {
 			for (const [pnUser, items] of pendingByPnUser.entries()) {
 				const lidUser = this.mappingCache.get(`pn:${pnUser}`)
 				for (const { pn, decoded } of items) {
-					if (lidUser) {
+					if (lidUser && decoded) {
 						const lidUserString = lidUser.toString()
 						if (!lidUserString) {
 							this.logger.warn({ pn, lidUser }, 'Invalid or empty LID user')
@@ -548,6 +548,8 @@ export class LIDMappingStore {
 						failedPns.add(pn)
 					}
 
+					if (!decoded) continue
+
 					// Need to fetch from USync
 					if (this.config.debugLogging) {
 						this.logger.trace({ pnUser }, 'No LID mapping found, queuing for USync')