diagnostics: Ensure that clean state is not shown when tab content indicates problems in workspace (#25345)

Closes #ISSUE

Release Notes:

- N/A *or* Added/Fixed/Improved ...

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>

crates/diagnostics/src/diagnostics.rs

@@ -88,15 +88,46 @@ const DIAGNOSTICS_UPDATE_DEBOUNCE: Duration = Duration::from_millis(50);
 
 impl Render for ProjectDiagnosticsEditor {
     fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
-        let child = if self.path_states.is_empty() {
+        let warning_count = if self.include_warnings {
-            div()
+            self.summary.warning_count
+        } else {
+            0
+        };
+
+        let child = if warning_count + self.summary.error_count == 0 {
+            let label = if self.summary.warning_count == 0 {
+                SharedString::new_static("No problems in workspace")
+            } else {
+                SharedString::new_static("No errors in workspace")
+            };
+            v_flex()
                 .key_context("EmptyPane")
-                .bg(cx.theme().colors().editor_background)
-                .flex()
-                .items_center()
-                .justify_center()
                 .size_full()
-                .child(Label::new("No problems in workspace"))
+                .gap_1()
+                .justify_center()
+                .items_center()
+                .text_center()
+                .bg(cx.theme().colors().editor_background)
+                .child(Label::new(label).color(Color::Muted))
+                .when(self.summary.warning_count > 0, |this| {
+                    let plural_suffix = if self.summary.warning_count > 1 {
+                        "s"
+                    } else {
+                        ""
+                    };
+                    let label = format!(
+                        "Show {} warning{}",
+                        self.summary.warning_count, plural_suffix
+                    );
+                    this.child(
+                        Button::new("diagnostics-show-warning-label", label).on_click(cx.listener(
+                            |this, _, window, cx| {
+                                this.toggle_warnings(&Default::default(), window, cx);
+                                cx.notify();
+                            },
+                        )),
+                    )
+                })
         } else {
             div().size_full().child(self.editor.clone())
         };