Early-out on zero-sized space-views to prevent crashes (#1623)

crates/re_viewer/src/ui/space_view.rs

@@ -143,6 +143,11 @@ impl SpaceView {
     ) {
         crate::profile_function!();
 
+        let is_zero_sized_viewport = ui.available_size().min_elem() <= 0.0;
+        if is_zero_sized_viewport {
+            return;
+        }
+
         let query = crate::ui::scene::SceneQuery {
             entity_paths: self.data_blueprint.entity_paths(),
             timeline: *ctx.rec_cfg.time_ctrl.timeline(),

crates/re_viewer/src/ui/view_spatial/ui_2d.rs

@@ -284,6 +284,10 @@ fn view_2d_scrollable(
     let (mut response, painter) =
         parent_ui.allocate_painter(desired_size, egui::Sense::click_and_drag());
 
+    if !response.rect.is_positive() {
+        return response; // protect against problems with zero-sized views
+    }
+
     // Create our transforms.
     let ui_from_space = egui::emath::RectTransform::from_to(scene_rect_accum, response.rect);
     let space_from_ui = ui_from_space.inverse();

crates/re_viewer/src/ui/view_spatial/ui_3d.rs

@@ -263,6 +263,10 @@ pub fn view_3d(
     let (rect, mut response) =
         ui.allocate_at_least(ui.available_size(), egui::Sense::click_and_drag());
 
+    if !rect.is_positive() {
+        return; // protect against problems with zero-sized views
+    }
+
     // If we're tracking a camera right now, we want to make it slightly sticky,
     // so that a click on some entity doesn't immediately break the tracked state.
     // (Threshold is in amount of ui points the mouse was moved.)