diff --git a/.gitignore b/.gitignore
index d46af8231..3684cd6dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,3 +41,6 @@ __pycache__/
 
 # Worktrees created for isolated runs
 .claude/worktrees/
+
+# Single-instance lock files the app writes next to an open drawing
+*.ocs.lock
diff --git a/src/app/update/file.rs b/src/app/update/file.rs
index 915fc0afa..bb43488b2 100644
--- a/src/app/update/file.rs
+++ b/src/app/update/file.rs
@@ -5119,8 +5119,8 @@ impl OpenCADStudio {
         d.apply_plot_styles = ps.flags.plot_plot_styles;
         d.show_plot_styles = ps.flags.show_plot_styles;
         d.style_missing = !d.style_name.is_empty() && !style_loaded;
-        self.refresh_custom_scale_fields();
         d.style_error = if d.style_missing { style_error } else { None };
+        self.refresh_custom_scale_fields();
     }
 
     /// Tell the user what a plot style table's loader had to tolerate.
diff --git a/src/io/print_to_printer.rs b/src/io/print_to_printer.rs
index 258928f73..ad68fea52 100644
--- a/src/io/print_to_printer.rs
+++ b/src/io/print_to_printer.rs
@@ -56,8 +56,8 @@ pub struct PrintOptions {
 }
 
 #[cfg(target_arch = "wasm32")]
-pub fn list_printers() -> Vec<String> {
-    Vec::new()
+pub fn list_printers() -> Result<Vec<String>, String> {
+    Ok(Vec::new())
 }
 
 #[cfg(target_arch = "wasm32")]
diff --git a/tests/fixtures/plot/.page-setups-metric.dxf.ocs.lock b/tests/fixtures/plot/.page-setups-metric.dxf.ocs.lock
deleted file mode 100644
index c6d7f094a..000000000
--- a/tests/fixtures/plot/.page-setups-metric.dxf.ocs.lock
+++ /dev/null
@@ -1 +0,0 @@
-Open CAD Studio pid=898490 path=/home/panos/OpenCADStudio/tests/fixtures/plot/page-setups-metric.dxf