Add basic ico support (#40822)

Closes https://github.com/zed-industries/zed/discussions/40763

<img width="867" height="1088" alt="Screenshot 2025-10-21 at 23 14 47"
src="https://github.com/user-attachments/assets/d691fb2a-afc6-4445-a335-054ef164e0d3"
/>

Also improves error handling on image open failure:

<img width="864" height="1083" alt="Screenshot 2025-10-21 at 23 14 30"
src="https://github.com/user-attachments/assets/d5388b61-995f-441b-b375-ad5136d1533b"
/>


Release Notes:

- Added basic ico support, improved unsupported image handling

crates/project/src/image_store.rs

@@ -687,6 +687,7 @@ fn create_gpui_image(content: Vec<u8>) -> anyhow::Result<Arc<gpui::Image>> {
             image::ImageFormat::Gif => gpui::ImageFormat::Gif,
             image::ImageFormat::Bmp => gpui::ImageFormat::Bmp,
             image::ImageFormat::Tiff => gpui::ImageFormat::Tiff,
+            image::ImageFormat::Ico => gpui::ImageFormat::Ico,
             format => anyhow::bail!("Image format {format:?} not supported"),
         },
         content,

crates/project/src/invalid_item_view.rs

@@ -0,0 +1,118 @@
+use std::{path::Path, sync::Arc};
+
+use gpui::{EventEmitter, FocusHandle, Focusable};
+use ui::{
+    App, Button, ButtonCommon, ButtonStyle, Clickable, Context, FluentBuilder, InteractiveElement,
+    KeyBinding, Label, LabelCommon, LabelSize, ParentElement, Render, SharedString, Styled as _,
+    Window, h_flex, v_flex,
+};
+use zed_actions::workspace::OpenWithSystem;
+
+use crate::Item;
+
+/// A view to display when a certain buffer fails to open.
+#[derive(Debug)]
+pub struct InvalidItemView {
+    /// Which path was attempted to open.
+    pub abs_path: Arc<Path>,
+    /// An error message, happened when opening the buffer.
+    pub error: SharedString,
+    is_local: bool,
+    focus_handle: FocusHandle,
+}
+
+impl InvalidItemView {
+    pub fn new(
+        abs_path: &Path,
+        is_local: bool,
+        e: &anyhow::Error,
+        _: &mut Window,
+        cx: &mut App,
+    ) -> Self {
+        Self {
+            is_local,
+            abs_path: Arc::from(abs_path),
+            error: format!("{}", e.root_cause()).into(),
+            focus_handle: cx.focus_handle(),
+        }
+    }
+}
+
+impl Item for InvalidItemView {
+    type Event = ();
+
+    fn tab_content_text(&self, mut detail: usize, _: &App) -> SharedString {
+        // Ensure we always render at least the filename.
+        detail += 1;
+
+        let path = self.abs_path.as_ref();
+
+        let mut prefix = path;
+        while detail > 0 {
+            if let Some(parent) = prefix.parent() {
+                prefix = parent;
+                detail -= 1;
+            } else {
+                break;
+            }
+        }
+
+        let path = if detail > 0 {
+            path
+        } else {
+            path.strip_prefix(prefix).unwrap_or(path)
+        };
+
+        SharedString::new(path.to_string_lossy())
+    }
+}
+
+impl EventEmitter<()> for InvalidItemView {}
+
+impl Focusable for InvalidItemView {
+    fn focus_handle(&self, _: &App) -> FocusHandle {
+        self.focus_handle.clone()
+    }
+}
+
+impl Render for InvalidItemView {
+    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl gpui::IntoElement {
+        let abs_path = self.abs_path.clone();
+        v_flex()
+            .size_full()
+            .track_focus(&self.focus_handle(cx))
+            .flex_none()
+            .justify_center()
+            .overflow_hidden()
+            .key_context("InvalidBuffer")
+            .child(
+                h_flex().size_full().justify_center().child(
+                    v_flex()
+                        .justify_center()
+                        .gap_2()
+                        .child(h_flex().justify_center().child("Could not open file"))
+                        .child(
+                            h_flex()
+                                .justify_center()
+                                .child(Label::new(self.error.clone()).size(LabelSize::Small)),
+                        )
+                        .when(self.is_local, |contents| {
+                            contents.child(
+                                h_flex().justify_center().child(
+                                    Button::new("open-with-system", "Open in Default App")
+                                        .on_click(move |_, _, cx| {
+                                            cx.open_with_system(&abs_path);
+                                        })
+                                        .style(ButtonStyle::Outlined)
+                                        .key_binding(KeyBinding::for_action(
+                                            &OpenWithSystem,
+                                            window,
+                                            cx,
+                                        )),
+                                ),
+                            )
+                        }),
+                ),
+            )
+    }
+}