warn on unloaded image render target

Author: ecoskey

crates/bevy_render/src/camera.rs

@@ -46,7 +46,7 @@ use bevy_window::{
     WindowScaleFactorChanged,
 };
 use derive_more::derive::From;
-use tracing::warn;
+use tracing::{error, warn};
 use wgpu::TextureFormat;
 
 #[derive(Default)]
@@ -235,11 +235,15 @@ impl NormalizedRenderTarget {
                     scale_factor: window.resolution.scale_factor(),
                 }),
             NormalizedRenderTarget::Image(image_target) => {
-                let image = images.get(&image_target.handle)?;
-                Some(RenderTargetInfo {
-                    physical_size: image.size(),
-                    scale_factor: image_target.scale_factor.0,
-                })
+                if let Some(image) = images.get(&image_target.handle) {
+                    Some(RenderTargetInfo {
+                        physical_size: image.size(),
+                        scale_factor: image_target.scale_factor.0,
+                    })
+                } else {
+                    error!("ImageRenderTarget handle unloaded. Make sure the Image's usages include RenderAssetUsages::MAIN_WORLD");
+                    None
+                }
             }
             NormalizedRenderTarget::TextureView(id) => {
                 manual_texture_views.get(id).map(|tex| RenderTargetInfo {
@@ -332,27 +336,31 @@ pub fn camera_system(
                 // This can happen when the window is moved between monitors with different DPIs.
                 // Without this, the viewport will take a smaller portion of the window moved to
                 // a higher DPI monitor.
-                if normalized_target
+                match normalized_target
                     .is_changed(&scale_factor_changed_window_ids, &HashSet::default())
                 {
-                    if let (Some(new_scale_factor), Some(old_scale_factor)) = (
-                        new_computed_target_info
-                            .as_ref()
-                            .map(|info| info.scale_factor),
-                        camera
-                            .computed
-                            .target_info
-                            .as_ref()
-                            .map(|info| info.scale_factor),
-                    ) {
-                        let resize_factor = new_scale_factor / old_scale_factor;
-                        if let Some(ref mut viewport) = camera.viewport {
-                            let resize = |vec: UVec2| (vec.as_vec2() * resize_factor).as_uvec2();
-                            viewport.physical_position = resize(viewport.physical_position);
-                            viewport.physical_size = resize(viewport.physical_size);
-                            viewport_size = Some(viewport.physical_size);
+                    true => {
+                        if let (Some(new_scale_factor), Some(old_scale_factor)) = (
+                            new_computed_target_info
+                                .as_ref()
+                                .map(|info| info.scale_factor),
+                            camera
+                                .computed
+                                .target_info
+                                .as_ref()
+                                .map(|info| info.scale_factor),
+                        ) {
+                            let resize_factor = new_scale_factor / old_scale_factor;
+                            if let Some(ref mut viewport) = camera.viewport {
+                                let resize =
+                                    |vec: UVec2| (vec.as_vec2() * resize_factor).as_uvec2();
+                                viewport.physical_position = resize(viewport.physical_position);
+                                viewport.physical_size = resize(viewport.physical_size);
+                                viewport_size = Some(viewport.physical_size);
+                            }
                         }
                     }
+                    false => (),
                 }
                 // This check is needed because when changing WindowMode to Fullscreen, the viewport may have invalid
                 // arguments due to a sudden change on the window size to a lower value.