settings_ui: Pre preview launch cleanup (#39733)

Closes #ISSUE

Release Notes:

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

---------

Co-authored-by: Anthony <anthony@zed.dev>

crates/settings/src/settings_content.rs

@@ -787,7 +787,9 @@ pub enum ShowIndentGuides {
 }
 
 #[skip_serializing_none]
-#[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq)]
+#[derive(
+    Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq, Default,
+)]
 pub struct IndentGuidesSettingsContent {
     /// When to show the scrollbar in the outline panel.
     pub show: Option<ShowIndentGuides>,

crates/settings/src/settings_content/terminal.rs

@@ -164,7 +164,9 @@ pub enum WorkingDirectory {
 }
 
 #[skip_serializing_none]
-#[derive(Clone, Copy, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq)]
+#[derive(
+    Clone, Copy, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq, Default,
+)]
 pub struct ScrollbarSettingsContent {
     /// When to show the scrollbar in the terminal.
     ///
@@ -203,6 +205,7 @@ impl TerminalLineHeight {
     Copy,
     Clone,
     Debug,
+    Default,
     Serialize,
     Deserialize,
     JsonSchema,
@@ -216,6 +219,7 @@ impl TerminalLineHeight {
 pub enum ShowScrollbar {
     /// Show the scrollbar if there's important information or
     /// follow the system's configured behavior.
+    #[default]
     Auto,
     /// Match the system's configured behavior.
     System,

crates/settings/src/settings_content/workspace.rs

@@ -418,7 +418,7 @@ pub enum PaneSplitDirectionVertical {
 }
 
 #[skip_serializing_none]
-#[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq)]
+#[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Default)]
 #[serde(rename_all = "snake_case")]
 pub struct CenteredLayoutSettings {
     /// The relative width of the left padding of the central pane from the
@@ -564,7 +564,9 @@ pub enum ProjectPanelEntrySpacing {
 }
 
 #[skip_serializing_none]
-#[derive(Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq)]
+#[derive(
+    Copy, Clone, Debug, Serialize, Deserialize, JsonSchema, MergeFrom, PartialEq, Eq, Default,
+)]
 pub struct ProjectPanelIndentGuidesSettings {
     pub show: Option<ShowIndentGuides>,
 }