Downgrade lack of our initial configure from error! to debug!

This can happen if a surface unmaps by committing a null buffer and then
immediately does the initial commit without a sync roundtrip, while there are
pending configures from the compositor in-flight. In this case, the surface
cannot tell that the pending configures were meant for "before unmapping" and
considers them to be the new initial configure.

From our point of view, we don't get to do a proper initial configuration
sequence in this case, and receive a mapping commit without our initial
configure state. We cannot really do much about it, but it is not an error when
this specific situation happens.

src/handlers/compositor.rs

@@ -115,7 +115,9 @@ impl CompositorHandler for State {
 
                             (rules, width, height, is_full_width, output, workspace_id)
                         } else {
-                            error!("window map must happen after initial configure");
+                            // Can happen when a surface unmaps by attaching a null buffer while
+                            // there are in-flight pending configures.
+                            debug!("window mapped without proper initial configure");
                             (ResolvedWindowRules::empty(), None, None, false, None, None)
                         };