Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: GordonSmith

src/extension.ts

@@ -457,7 +457,10 @@ export function activate(context: vscode.ExtensionContext) {
                 try {
                     await vscode.commands.executeCommand("vscode.open", saveUri);
                 } catch {
-                    // As a fallback just leave it saved and inform the user; they can use Open With... Hex Editor
+                } catch (openError) {
+                    vscode.window.showWarningMessage(
+                        `Core wasm was extracted and saved to ${saveUri.fsPath}, but could not be opened automatically. You can open it manually (e.g., with "Open With... Hex Editor").`
+                    );
                 }
             } catch (error) {
                 console.error("extractCoreWasm failed:", error);