Panics when opening tutor.

[getreu]

Summary

$ hx --tutor
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', /home/runner/work/helix/helix/helix-term/src/application.rs:509:43
```


### Reproduction Steps

I tried this:

1. `hx`
2. Type `:tutor`
3. Wait a bit and move around with cursor.

I expected this to happen:

No panic.

Instead, this happened:

```sh
$ hx
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', /home/runner/work/helix/helix/helix-term/src/application.rs:509:43
```


### Helix log

<details><summary>~/.cache/helix/helix.log</summary>

```
2022-09-04T09:36:41.199 helix_loader [DEBUG] Located configuration folders: []
2022-09-04T09:36:41.208 helix_view::clipboard [INFO] Using xclip to interact with the system and selection (primary) clipboard
2022-09-04T09:36:41.274 helix_lsp::transport [INFO] -> {"jsonrpc":"2.0","method":"initialize","params":{"capabilities":{"textDocument":{"codeAction":{"codeActionLiteralSupport":{"codeActionKind":{"valueSet":["","quickfix","refactor","refactor.extract","refactor.inline","refactor.rewrite","source","source.organizeImports"]}}},"completion":{"completionItem":{"resolveSupport":{"properties":["documentation","detail","additionalTextEdits"]},"snippetSupport":false},"completionItemKind":{}},"hover":{"contentFormat":["markdown"]},"publishDiagnostics":{},"rename":{"dynamicRegistration":false,"honorsChangeAnnotations":false,"prepareSupport":false},"signatureHelp":{"signatureInformation":{"activeParameterSupport":true,"documentationFormat":["markdown"],"parameterInformation":{"labelOffsetSupport":true}}}},"window":{"workDoneProgress":true},"workspace":{"applyEdit":true,"configuration":true,"didChangeConfiguration":{"dynamicRegistration":false},"symbol":{"dynamicRegistration":false},"workspaceFolders":true}},"processId":6202,"rootUri":null,"workspaceFolders":[]},"id":0}
2022-09-04T09:36:44.764 helix_lsp::transport [ERROR] err <- "Sep 04, 2022 9:36:44 AM org.bsplines.ltexls.server.LtexLanguageServer initialize\n"
2022-09-04T09:36:44.764 helix_lsp::transport [ERROR] err <- "INFO: ltex-ls 15.2.1-alpha.1.nightly.2022-04-18 - initializing...\n"
2022-09-04T09:36:44.799 helix_lsp::transport [INFO] <- {"jsonrpc":"2.0","id":0,"result":{"capabilities":{"textDocumentSync":1,"completionProvider":{},"codeActionProvider":{"codeActionKinds":["quickfix.ltex.acceptSuggestions"]},"executeCommandProvider":{"commands":["_ltex.checkDocument","_ltex.getServerStatus"]}}}}
2022-09-04T09:36:44.800 helix_lsp::transport [INFO] <- {"capabilities":{"codeActionProvider":{"codeActionKinds":["quickfix.ltex.acceptSuggestions"]},"completionProvider":{},"executeCommandProvider":{"commands":["_ltex.checkDocument","_ltex.getServerStatus"]},"textDocumentSync":1}}
2022-09-04T09:36:44.800 helix_lsp::transport [INFO] -> {"jsonrpc":"2.0","method":"initialized","params":{}}
```

</details>


### Platform

Linux

### Terminal Emulator

xfce4-terminal 0.8.10 (Xfce 4.16)

### Helix Version

helix 22.08 (ee94031f)

[archseer]

Seems to be the LSP:

helix/helix-term/src/application.rs

Line 509 in f0d1caa

doc.url().unwrap(),

We should only send didOpen events for documents with a path