fix(common): servers.startOnPort() error handling

Promise no longer hangs if error event is fired on the server object

Fixes hyperledger-cacti#317

Signed-off-by: Peter Somogyvari <peter.somogyvari@accenture.com>

packages/cactus-common/src/main/typescript/servers.ts

@@ -96,6 +96,7 @@ export class Servers {
     const server: Server = await new Promise((resolve, reject) => {
       const aServer: Server = createServer();
       aServer.once("listening", () => resolve(aServer));
+      aServer.once("error", (err: Error) => reject(err));
       aServer.listen(port, "localhost");
     });