Fix crash

Source/Debugging.swift

@@ -107,11 +107,11 @@ private var labelKey = ""
 private func descriptionForObject(object: AnyObject) -> String {
     let pointerDescription = NSString(format: "%p", [object])
     if let object = object as? View {
-        return "<\(object.dynamicType):\(object.snp_label ?? pointerDescription)>"
+        return "<\(object.dynamicType.description()):\(object.snp_label ?? pointerDescription)>"
     } else if let object = object as? LayoutConstraint {
-        return "<\(object.dynamicType):\(object.snp_label ?? pointerDescription)>"
+        return "<\(object.dynamicType.description()):\(object.snp_label ?? pointerDescription)>"
     }
-    return "<\(object.dynamicType):\(pointerDescription)>"
+    return "<\(object.dynamicType.description()):\(pointerDescription)>"
 }
 
 private extension NSLayoutRelation {