Handle syntax errors.

layouts/error.hbs

@@ -0,0 +1,17 @@
+<html lang="en">
+
+{{> (include_partial "layouts/partials/head") }}
+
+<body>
+
+<main>
+  <div class="container" style="max-width: 1280px; margin: 1rem auto;">
+    <h1>Syntax Error:</h1>
+    <pre style="padding: 10px 15px; background-color: #ffe6e6; border: 1px solid red; border-radius: 0.25rem; overflow: auto">{{err}}</pre>
+  </div>
+</main>
+
+{{> (include_partial "layouts/partials/scripts") }}
+
+</body>
+</html>