Fix crash in MDX whitespace

Related-to: GH-26.
Closes GH-60.

Author: mickvangelderen

src/construct/partial_mdx_jsx.rs

@@ -1070,17 +1070,19 @@ pub fn es_whitespace_inside(tokenizer: &mut Tokenizer) -> State {
             tokenizer.consume();
             State::Next(StateName::MdxJsxEsWhitespaceInside)
         }
-        _ => {
+        Some(_)
             if kind_after_index(tokenizer.parse_state.bytes, tokenizer.point.index)
-                == CharacterKind::Whitespace
-            {
-                tokenizer.consume();
-                State::Next(StateName::MdxJsxEsWhitespaceInside)
-            } else {
-                tokenizer.exit(Name::MdxJsxEsWhitespace);
-                State::Ok
-            }
+                == CharacterKind::Whitespace =>
+        {
+            tokenizer.consume();
+            State::Next(StateName::MdxJsxEsWhitespaceInside)
+        }
+        Some(_) => {
+            tokenizer.exit(Name::MdxJsxEsWhitespace);
+            State::Ok
         }
+        // Handle EOF.
+        None => State::Nok,
     }
 }
 

tests/fuzz.rs

@@ -117,5 +117,17 @@ fn fuzz() -> Result<(), String> {
         "11: gfm task list items followed by eols (GH-24)"
     );
 
+    assert_eq!(
+        markdown::to_html_with_options(
+            "<",
+            &markdown::Options {
+                parse: markdown::ParseOptions::mdx(),
+                ..Default::default()
+            }
+        ),
+        Ok("<p>&lt;</p>".to_string()),
+        "12: mdx: handle invalid mdx without panic (GH-26)"
+    );
+
     Ok(())
 }