make serialization of xml and html fallible

Author: mukilan

components/script/dom/element.rs

@@ -3831,6 +3831,7 @@ impl ElementMethods<crate::DomTypeHolder> for Element {
         } else {
             self.upcast::<Node>()
                 .xml_serialize(XmlChildrenOnly(Some(qname)))
+                .map_err(|_| Error::InvalidState)?
         };
 
         Ok(TrustedHTMLOrNullIsEmptyString::NullIsEmptyString(result))
@@ -3888,7 +3889,9 @@ impl ElementMethods<crate::DomTypeHolder> for Element {
             self.upcast::<Node>()
                 .html_serialize(IncludeNode, false, vec![], can_gc)
         } else {
-            self.upcast::<Node>().xml_serialize(XmlIncludeNode)
+            self.upcast::<Node>()
+                .xml_serialize(XmlIncludeNode)
+                .map_err(|_| Error::InvalidState)?
         };
 
         Ok(TrustedHTMLOrNullIsEmptyString::NullIsEmptyString(result))

components/script/dom/node.rs

@@ -3150,17 +3150,17 @@ impl Node {
     pub(crate) fn xml_serialize(
         &self,
         traversal_scope: xml_serialize::TraversalScope,
-    ) -> DOMString {
+    ) -> Result<DOMString, ()> {
         let mut writer = vec![];
         xml_serialize::serialize(
             &mut writer,
             &self,
             xml_serialize::SerializeOpts { traversal_scope },
         )
-        .expect("Cannot serialize node");
+        .map_err(|_| ())?;
 
         // FIXME(ajeffrey): Directly convert UTF8 to DOMString
-        DOMString::from(String::from_utf8(writer).unwrap())
+        Ok(DOMString::from(String::from_utf8(writer).unwrap()))
     }
 
     /// <https://html.spec.whatwg.org/multipage/#fragment-serializing-algorithm-steps>
@@ -3187,6 +3187,7 @@ impl Node {
         // TODO: xml5ever doesn't seem to want require_well_formed
         let _ = require_well_formed;
         self.xml_serialize(xml_serialize::TraversalScope::ChildrenOnly(None))
+            .unwrap()
     }
 }