Avoid a hang on linux by always create the renderer, even when we have no store_view (#5724)

### What
- Mitigates: #5283

All this does is re-orders the calls so that we always create a renderer
and call begin_frame / before_submit even if the case where we have no
StoreView.

In theory this uses a few more resources when skipping the welcome
screen, but practically in almost all cases this is only for a few
frames until log-data starts arriving.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/5724/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5724/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/5724/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
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usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5724)
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Author: jleibs

crates/re_viewer/src/app.rs

@@ -847,19 +847,23 @@ impl App {
 
                 self.egui_debug_panel_ui(ui);
 
-                if let Some(store_view) = store_context {
-                    let entity_db = store_view.recording;
-
-                    // TODO(andreas): store the re_renderer somewhere else.
-                    let egui_renderer = {
-                        let render_state = frame.wgpu_render_state().unwrap();
-                        &mut render_state.renderer.write()
-                    };
-                    if let Some(render_ctx) = egui_renderer
-                        .callback_resources
-                        .get_mut::<re_renderer::RenderContext>()
-                    {
-                        render_ctx.begin_frame();
+                // TODO(andreas): store the re_renderer somewhere else.
+                let egui_renderer = {
+                    let render_state = frame.wgpu_render_state().unwrap();
+                    &mut render_state.renderer.write()
+                };
+
+                if let Some(render_ctx) = egui_renderer
+                    .callback_resources
+                    .get_mut::<re_renderer::RenderContext>()
+                {
+                    // TODO(#5283): There's no great reason to do this if we have no store-view and
+                    // subsequently won't actually be rendering anything. However, doing this here
+                    // avoids a hang on linux. Consider moving this back inside the below `if let`.
+                    // once the upstream issues that fix the hang properly have been resolved.
+                    render_ctx.begin_frame();
+                    if let Some(store_view) = store_context {
+                        let entity_db = store_view.recording;
 
                         self.state.show(
                             app_blueprint,
@@ -873,15 +877,8 @@ impl App {
                             &self.rx,
                             &self.command_sender,
                         );
-
-                        render_ctx.before_submit();
                     }
-                } else {
-                    // There's nothing to show.
-                    // We get here when
-                    // A) there is nothing loaded
-                    // B) we decided not to show the welcome screen, presumably because data is expected at any time now.
-                    // The user can see the connection status in the top bar.
+                    render_ctx.before_submit();
                 }
             });
     }