It looks like deleted entities still appear in search results, with the backup "(unnamed)" titles since it can't find a current alias.

Entities with no `dataId` field should be filtered out of the results.

It looks like the entity is not being removed from the search index because of the following error:
```
(node:42) UnhandledPromiseRejectionWarning: ConfigurationError: Missing required parameter: id
at _delete (/home/bookbrainz/bookbrainz-site/node_modules/@elastic/elasticsearch/api/api/delete.js:64:19)
at Client._lazyLoad [as delete] (/home/bookbrainz/bookbrainz-site/node_modules/@elastic/elasticsearch/api/index.js:249:12)
at deleteEntity (/home/bookbrainz/bookbrainz-site/lib/common/helpers/search.js:460:24)
at _callee$ (/home/bookbrainz/bookbrainz-site/lib/server/helpers/handler.js:64:46)
at tryCatch (/home/bookbrainz/bookbrainz-site/node_modules/@babel/runtime/node_modules/regenerator-runtime/runtime.js:45:40)
at Generator.invoke [as _invoke] (/home/bookbrainz/bookbrainz-site/node_modules/@babel/runtime/node_modules/regenerator-runtime/runtime.js:274:22)
at Generator.prototype.(anonymous function) [as next] (/home/bookbrainz/bookbrainz-site/node_modules/@babel/runtime/node_modules/regenerator-runtime/runtime.js:97:21)
at asyncGeneratorStep (/home/bookbrainz/bookbrainz-site/node_modules/@babel/runtime/helpers/asyncToGenerator.js:3:24)
at _next (/home/bookbrainz/bookbrainz-site/node_modules/@babel/runtime/helpers/asyncToGenerator.js:25:9)
at process._tickCallback (internal/process/next_tick.js:68:7)
(node:42) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)
(node:42) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
```