cli: highlight "Error: " headings

cli/src/command_error.rs

@@ -500,11 +500,11 @@ fn try_handle_command_result(
     let hints = &cmd_err.hints;
     match cmd_err.kind {
         CommandErrorKind::User => {
-            print_error(ui, "Error", err, hints)?;
+            print_error(ui, "Error: ", err, hints)?;
             Ok(ExitCode::from(1))
         }
         CommandErrorKind::Config => {
-            print_error(ui, "Config error", err, hints)?;
+            print_error(ui, "Config error: ", err, hints)?;
             writeln!(
                 ui.hint_no_heading(),
                 "For help, see https://github.com/martinvonz/jj/blob/main/docs/config.md."
@@ -515,7 +515,7 @@ fn try_handle_command_result(
             if let Some(err) = err.downcast_ref::<clap::Error>() {
                 handle_clap_error(ui, err, hints)
             } else {
-                print_error(ui, "Error", err, hints)?;
+                print_error(ui, "Error: ", err, hints)?;
                 Ok(ExitCode::from(2))
             }
         }
@@ -524,14 +524,14 @@ fn try_handle_command_result(
             Ok(ExitCode::from(BROKEN_PIPE_EXIT_CODE))
         }
         CommandErrorKind::Internal => {
-            print_error(ui, "Internal error", err, hints)?;
+            print_error(ui, "Internal error: ", err, hints)?;
             Ok(ExitCode::from(255))
         }
     }
 }
 
-fn print_error(ui: &Ui, prefix: &str, err: &dyn error::Error, hints: &[String]) -> io::Result<()> {
-    writeln!(ui.error(), "{prefix}: {err}")?;
+fn print_error(ui: &Ui, heading: &str, err: &dyn error::Error, hints: &[String]) -> io::Result<()> {
+    writeln!(ui.error_with_heading(heading), "{err}")?;
     print_error_sources(ui, err.source())?;
     for hint in hints {
         writeln!(ui.hint_with_heading("Hint: "), "{hint}")?;

cli/src/config/colors.toml

@@ -2,6 +2,7 @@
 "error" = "red"
 "warning" = "yellow"
 "hint" = "cyan"
+"error heading" = { bold = true }
 "warning heading" = { bold = true }
 "hint heading" = { bold = true }
 

cli/src/templater.rs

@@ -679,8 +679,10 @@ where
 
 fn format_error_inline(formatter: &mut dyn Formatter, err: &dyn error::Error) -> io::Result<()> {
     formatter.with_label("error", |formatter| {
-        write!(formatter, "<Error")?;
-        for err in iter::successors(Some(err), |err| err.source()) {
+        write!(formatter, "<")?;
+        write!(formatter.labeled("heading"), "Error: ")?;
+        write!(formatter, "{err}")?;
+        for err in iter::successors(err.source(), |err| err.source()) {
             write!(formatter, ": {err}")?;
         }
         write!(formatter, ">")?;

cli/src/ui.rs

@@ -399,10 +399,19 @@ impl Ui {
         HeadingLabeledWriter::new(self.stderr_formatter(), "warning", heading)
     }
 
-    pub fn error(&self) -> LabeledWriter<Box<dyn Formatter + '_>, &'static str> {
+    /// Writer to print error without the "Error: " heading.
+    pub fn error_no_heading(&self) -> LabeledWriter<Box<dyn Formatter + '_>, &'static str> {
         LabeledWriter::new(self.stderr_formatter(), "error")
     }
 
+    /// Writer to print error with the given heading.
+    pub fn error_with_heading<H: fmt::Display>(
+        &self,
+        heading: H,
+    ) -> HeadingLabeledWriter<Box<dyn Formatter + '_>, &'static str, H> {
+        HeadingLabeledWriter::new(self.stderr_formatter(), "error", heading)
+    }
+
     /// Waits for the pager exits.
     #[instrument(skip_all)]
     pub fn finalize_pager(&mut self) {
@@ -416,7 +425,7 @@ impl Ui {
                     // It's possible (though unlikely) that this write fails, but
                     // this function gets called so late that there's not much we
                     // can do about it.
-                    writeln!(self.error(), "Failed to wait on pager: {e}").ok();
+                    writeln!(self.error_no_heading(), "Failed to wait on pager: {e}").ok();
                 }
             }
             UiOutput::BuiltinPaged { pager } => {

cli/tests/test_global_opts.rs

@@ -397,14 +397,31 @@ fn test_color_ui_messages() {
     insta::assert_snapshot!(stderr, @r###"
     Hint: Use `jj -h` for a list of available commands.
     Run `jj config set --user ui.default-command log` to disable this message.
-    [38;5;1mError: There is no jj repo in "."[39m
+    [1m[38;5;1mError: [0m[38;5;1mThere is no jj repo in "."[39m
     "###);
 
     // warning
     let (_stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["log", "@"]);
     insta::assert_snapshot!(stderr, @r###"
     warning: The argument "@" is being interpreted as a path. To specify a revset, pass -r "@" instead.
     "###);
+
+    // error inlined in template output
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
+    let stdout = test_env.jj_cmd_success(
+        &repo_path,
+        &[
+            "log",
+            "-r@|@--",
+            "--config-toml=templates.log_node='commit_id'",
+            "-Tdescription",
+        ],
+    );
+    insta::assert_snapshot!(stdout, @r###"
+    8bb159bc30a9859930e567eb9238a7c43ee6744d
+    <Error: No commit available>  (elided revisions)
+    0000000000000000000000000000000000000000
+    "###);
 }
 
 #[test]