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/workspace/src/invalid_item_view.rs

@@ -10,17 +10,17 @@ use zed_actions::workspace::OpenWithSystem;
 
 use crate::Item;
 
-/// A view to display when a certain buffer fails to open.
-pub struct InvalidBufferView {
+/// A view to display when a certain buffer/image/other item fails to open.
+pub struct InvalidItemView {
     /// Which path was attempted to open.
     pub abs_path: Arc<Path>,
-    /// An error message, happened when opening the buffer.
+    /// An error message, happened when opening the item.
     pub error: SharedString,
     is_local: bool,
     focus_handle: FocusHandle,
 }
 
-impl InvalidBufferView {
+impl InvalidItemView {
     pub fn new(
         abs_path: &Path,
         is_local: bool,
@@ -37,7 +37,7 @@ impl InvalidBufferView {
     }
 }
 
-impl Item for InvalidBufferView {
+impl Item for InvalidItemView {
     type Event = ();
 
     fn tab_content_text(&self, mut detail: usize, _: &App) -> SharedString {
@@ -66,15 +66,15 @@ impl Item for InvalidBufferView {
     }
 }
 
-impl EventEmitter<()> for InvalidBufferView {}
+impl EventEmitter<()> for InvalidItemView {}
 
-impl Focusable for InvalidBufferView {
+impl Focusable for InvalidItemView {
     fn focus_handle(&self, _: &App) -> FocusHandle {
         self.focus_handle.clone()
     }
 }
 
-impl Render for InvalidBufferView {
+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()
@@ -83,7 +83,7 @@ impl Render for InvalidBufferView {
             .flex_none()
             .justify_center()
             .overflow_hidden()
-            .key_context("InvalidBuffer")
+            .key_context("InvalidItem")
             .child(
                 h_flex().size_full().justify_center().child(
                     v_flex()

crates/workspace/src/item.rs

@@ -1,7 +1,7 @@
 use crate::{
     CollaboratorId, DelayedDebouncedEditAction, FollowableViewRegistry, ItemNavHistory,
     SerializableItemRegistry, ToolbarItemLocation, ViewId, Workspace, WorkspaceId,
-    invalid_buffer_view::InvalidBufferView,
+    invalid_item_view::InvalidItemView,
     pane::{self, Pane},
     persistence::model::ItemId,
     searchable::SearchableItemHandle,
@@ -1062,7 +1062,7 @@ pub trait ProjectItem: Item {
         _e: &anyhow::Error,
         _window: &mut Window,
         _cx: &mut App,
-    ) -> Option<InvalidBufferView>
+    ) -> Option<InvalidItemView>
     where
         Self: Sized,
     {

crates/workspace/src/pane.rs

@@ -2,7 +2,7 @@ use crate::{
     CloseWindow, NewFile, NewTerminal, OpenInTerminal, OpenOptions, OpenTerminal, OpenVisible,
     SplitDirection, ToggleFileFinder, ToggleProjectSymbols, ToggleZoom, Workspace,
     WorkspaceItemBuilder,
-    invalid_buffer_view::InvalidBufferView,
+    invalid_item_view::InvalidItemView,
     item::{
         ActivateOnClose, ClosePosition, Item, ItemBufferKind, ItemHandle, ItemSettings,
         PreviewTabsSettings, ProjectItemKind, SaveOptions, ShowCloseButton, ShowDiagnostics,
@@ -992,11 +992,11 @@ impl Pane {
 
             let new_item = build_item(self, window, cx);
             // A special case that won't ever get a `project_entry_id` but has to be deduplicated nonetheless.
-            if let Some(invalid_buffer_view) = new_item.downcast::<InvalidBufferView>() {
+            if let Some(invalid_buffer_view) = new_item.downcast::<InvalidItemView>() {
                 let mut already_open_view = None;
                 let mut views_to_close = HashSet::default();
                 for existing_error_view in self
-                    .items_of_type::<InvalidBufferView>()
+                    .items_of_type::<InvalidItemView>()
                     .filter(|item| item.read(cx).abs_path == invalid_buffer_view.read(cx).abs_path)
                 {
                     if already_open_view.is_none()

crates/workspace/src/workspace.rs

@@ -1,6 +1,6 @@
 pub mod dock;
 pub mod history_manager;
-pub mod invalid_buffer_view;
+pub mod invalid_item_view;
 pub mod item;
 mod modal_layer;
 pub mod notifications;