Enhance server side error handling (#4537)

* fix: server side error handling

* fix: push only unknown 500 errors to sentry

* fix: use in-house onerror in favor of errorHandling middleware

* fix: split error template into dev and prod envs

* fix: check Error instance

* fix: error routes in test env

* fix: review comments

* Remove koa-onerror

Co-authored-by: Tom Moor <tom.moor@gmail.com>

server/routes/api/documents/__snapshots__/documents.test.ts.snap

@@ -5,6 +5,7 @@ Object {
   "error": "authorization_error",
   "message": "Authorization error",
   "ok": false,
+  "status": 403,
 }
 `;