Fix no previewer for no-code demos

Author: theCapypara

src/Previewer/Previewer.js

@@ -161,7 +161,7 @@ export default function Previewer({
     if (settings.get_boolean("auto-preview")) schedule_update();
   });
   let symbols = null;
-  async function update(force = false) {
+  async function update(force = false, clearConsole = true) {
     if (!(force || settings.get_boolean("auto-preview"))) return;
     let text = panel_ui.xml.trim();
     let target_id;
@@ -203,7 +203,9 @@ export default function Previewer({
 
     registerSignals({ tree, scope, symbols, template });
 
-    term_console.clear();
+    if (clearConsole) {
+      term_console.clear();
+    }
 
     try {
       builder.add_from_string(text, -1);

src/window.js

@@ -329,6 +329,9 @@ export default function Window({ application, session }) {
 
     previewer.start();
     panel_ui.start();
+    // We already cleared the console before starting.
+    // We don't want to clear the console again, as this would hide compile errors if any occurred.
+    await previewer.update(true, false);
 
     button_run.set_sensitive(true);
     term_console.scrollToEnd();
@@ -345,8 +348,6 @@ export default function Window({ application, session }) {
     }
 
     if (language === "JavaScript") {
-      await previewer.update(true);
-
       // We have to create a new file each time
       // because gjs doesn't appear to use etag for module caching
       // ?foo=Date.now() also does not work as expected