graceful fallback for missing footnotes (#227)

* add failing test for #226

* graceful fallback for missing footnotes

fixes #226

* raise the size threshold slightly

index.compiler.spec.js

@@ -2673,6 +2673,17 @@ describe('footnotes', () => {
   </footer>
 </div>
 
+`);
+  });
+
+  it('should not blow up if footnote syntax is seen but no matching footnote was found', () => {
+    expect(() => render(compiler('[one] [two]'))).not.toThrow();
+    expect(root.innerHTML).toMatchInlineSnapshot(`
+
+<span data-reactroot>
+  [one] [two]
+</span>
+
 `);
   });
 });

index.js

@@ -164,6 +164,7 @@ const PARAGRAPH_R = /^((?:[^\n]|\n(?! *\n))+)(?:\n *)+\n/;
 const REFERENCE_IMAGE_OR_LINK = /^\[([^\]]*)\]:\s*(\S+)\s*("([^"]*)")?/;
 const REFERENCE_IMAGE_R = /^!\[([^\]]*)\] ?\[([^\]]*)\]/;
 const REFERENCE_LINK_R = /^\[([^\]]*)\] ?\[([^\]]*)\]/;
+const SQUARE_BRACKETS_R = /(\[|\])/g;
 const SHOULD_RENDER_AS_BLOCK_R = /(\n|^[-*]\s|^#|^ {2,}|^-{2,}|^>\s)/;
 const TAB_R = /\t/g;
 const TABLE_TRIM_PIPES = /(^ *\||\| *$)/g;
@@ -1373,19 +1374,20 @@ export function compiler(markdown, options) {
       parse(capture, parse, state) {
         return {
           content: parse(capture[1], state),
+          fallbackContent: parse(capture[0].replace(SQUARE_BRACKETS_R, '\\$1'), state),
           ref: capture[2],
         };
       },
       react(node, output, state) {
-        return (
+        return refs[node.ref] ? (
           <a
             key={state.key}
             href={sanitizeUrl(refs[node.ref].target)}
             title={refs[node.ref].title}
           >
             {output(node.content, state)}
           </a>
-        );
+        ) : <span>{output(node.fallbackContent, state)}</span>;
       },
     },
 

package.json

@@ -83,7 +83,7 @@
   "size-limit": [
     {
       "path": "dist/cjs.js",
-      "limit": "5 kB"
+      "limit": "5.15 kB"
     }
   ],
   "jest": {