fix: fix type issue

Author: jaulz

src/constructs/aws/ServerSideWebsite.ts

@@ -129,7 +129,7 @@ export class ServerSideWebsite extends AwsConstruct {
                 : undefined;
 
         // Hide the stage in the URL in REST scenario
-        const originPath = configuration.apiGateway === "rest" ? "/" + provider.getStage() : undefined;
+        const originPath = configuration.apiGateway === "rest" ? "/" + (provider.getStage() ?? "") : undefined;
 
         this.distribution = new Distribution(this, "CDN", {
             comment: `${provider.stackName} ${id} website CDN`,

src/providers/AwsProvider.ts

@@ -146,7 +146,7 @@ export class AwsProvider implements ProviderInterface {
      *
      * @internal
      */
-    getStage(): string {
+    getStage(): string | undefined {
         return this.serverless.service.provider.stage;
     }