config: use dirname so we don't have to alloc a new dir for edit

src/config/edit.zig

@@ -5,24 +5,22 @@ const internal_os = @import("../os/main.zig");
 /// Open the configuration in the OS default editor according to the default
 /// paths the main config file could be in.
 pub fn open(alloc_gpa: Allocator) !void {
-    // default dir
-    const config_dir = try internal_os.xdg.config(alloc_gpa, .{ .subdir = "ghostty" });
     // default location
     const config_path = try internal_os.xdg.config(alloc_gpa, .{ .subdir = "ghostty/config" });
+    defer alloc_gpa.free(config_path);
 
-    defer {
+    // Check if the directory exists, create it if it doesn't. This dirname
-        alloc_gpa.free(config_path);
+    // call should always succeed but we still check for errors just in case,
-        alloc_gpa.free(config_dir);
+    // no harm if we skip this step the open may just fail.
+    if (std.fs.path.dirname(config_path)) |config_dir| {
+        _ = std.fs.makeDirAbsolute(config_dir) catch |err| {
+            switch (err) {
+                error.PathAlreadyExists => {},
+                else => return err,
+            }
+        };
     }
 
-    // Check if the directory exists, create it if it doesn't
-    _ = std.fs.makeDirAbsolute(config_dir) catch |err| {
-        switch (err) {
-            error.PathAlreadyExists => {},
-            else => return err,
-        }
-    };
-
     // Try to create file and go on if it already exists
     _ = std.fs.createFileAbsolute(
         config_path,