[FIX] base: bootstrap css load issue fixed for asset mode

When you was in debug=assets and that a less file was malformed, the
error was not displayed correctly.

Now we load a minimal layout (bootstrap style)

This commit closes #19799

odoo/addons/base/ir/ir_qweb/assetsbundle.py

@@ -112,8 +112,11 @@ class AssetsBundle(object):
                     if self.css_errors:
                         msg = '\n'.join(self.css_errors)
                         response.append(JavascriptAsset(self, inline=self.dialog_message(msg)).to_html())
-                for style in self.stylesheets:
-                    response.append(style.to_html())
+                        response.append(StylesheetAsset(self, url="/web/static/lib/bootstrap/css/bootstrap.css").to_html())
+                if not self.css_errors:
+                    for style in self.stylesheets:
+                        response.append(style.to_html())
+
             if js:
                 for jscript in self.javascripts:
                     response.append(jscript.to_html())