Extra Stat collection (#407)

* Cleaned up error interceptor to avoid sending auth errors (when a 500 occurs) to sentry as auth errors aren't issues.

* Added extra stat collection

* Fixed a bad gitignore which ignored anything in a stats directory

UI/Web/src/app/_models/stats/client-info.ts

@@ -7,6 +7,7 @@ export interface ClientInfo {
     platformType: string,
     kavitaUiVersion: string,
     screenResolution: string;
+    usingDarkTheme: boolean;
 
     collectedAt?: Date;
 }