Fix lints

@@ -142,7 +142,7 @@ class PdfGraphicState {
   }
 
   @override
-  bool operator ==(dynamic other) {
+  bool operator ==(Object other) {
     if (other is! PdfGraphicState) {
       return false;
     }

@@ -88,7 +88,10 @@ mixin Printing {
         return a.name.compareTo(b.name);
       });
 
-      // ignore: use_build_context_synchronously
+      if (!context.mounted) {
+        return null;
+      }
+
       return await showDialog<Printer>(
         context: context,
         builder: (context) => SimpleDialog(