Joincol with no column to the right and Theme with no such theme say so

Both did nothing without a word, from a click or a ctl write alike, and a
script could not tell a no-op from success. Joincol in the rightmost column
now fails 'Joincol: no column to the right'. A Theme name that is none says so
and names the themes sharing its first letter, since all of them (ThemeSel
lists them) are too many for a message or a refused write; a startup config
line still fails quietly, as its other bad lines do.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/exec.zig b/src/exec.zig
index b16c600c..2faf84de 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -467,6 +467,12 @@ pub fn applySettingBuiltin(p: *Pardes, setting: config.Runtime.Setting, arg: ?[]
                 colors.setThemeIndex(p, i);
                 return;
             };
+            // A config line is not answered on screen (applyStartupConfig
+            // runs with announce off); a click or a ctl write is.
+            if (!p.announce) return;
+            var near: [96]u8 = undefined;
+            var text: [200]u8 = undefined;
+            return p.reportFailure(p.active, std.fmt.bufPrint(&text, "Theme: no theme \"{s}\"; like it: {s}; ThemeSel lists all", .{ want[0..@min(want.len, 40)], colors.themesNear(&near, want) }) catch "Theme: no such theme");
         },
         .font => {
             if (comptime !font_picker) return;