SenseApiMgr: Print dev info when detaching, use early return pattern

senseApis/xcbWindow/xcbWindow.cpp

@@ -312,15 +312,17 @@ static int xcbWindow_detachDeviceReq(const smo::device::SenseDeviceSpec& spec)
         }
     );
 
-    if (it != g_attachedWindows.end())
+    if (it == g_attachedWindows.end())
     {
-        g_attachedWindows.erase(it);
-        std::cout << __func__ << ": Detached X11 window device\n";
-        return 0;
+        std::cerr << __func__ << ": Device not found for detachment:\n"
+            << spec.stringify() << "\n";
+        return -1;
     }
 
-    std::cerr << __func__ << ": Device not found for detachment\n";
-    return -1;
+    g_attachedWindows.erase(it);
+    std::cout << __func__ << ": Detached X11 window device:\n"
+        << spec.stringify() << "\n";
+    return 0;
 }
 
 // SenseApi descriptor