Print playground AST with Prettier to make it easier to read

website/static/worker.js

@@ -33,14 +33,21 @@ self.onmessage = function(message) {
   var ast;
 
   if (message.data.ast) {
+    var actualAst;
+    var errored = false;
     try {
-      ast = JSON.stringify(
-        prettier.__debug.parse(message.data.text, options),
-        null,
-        2
-      );
+      actualAst = prettier.__debug.parse(message.data.text, options);
+      ast = JSON.stringify(actualAst);
     } catch (e) {
-      ast = e.toString();
+      errored = true;
+      ast = String(e);
+    }
+    if (!errored) {
+      try {
+        ast = formatCode(ast, { parser: "json" });
+      } catch (e) {
+        ast = JSON.stringify(actualAst, null, 2);
+      }
     }
   }
 
@@ -52,7 +59,7 @@ self.onmessage = function(message) {
         { parser: "babylon" }
       );
     } catch (e) {
-      doc = e.toString();
+      doc = String(e);
     }
   }
 
@@ -70,7 +77,7 @@ function formatCode(text, options) {
       lazyLoadParser(e.parser);
       return formatCode(text, options);
     }
-    return e.toString();
+    return String(e);
   }
 }