fix: improve REPL stringify logic (#11609)

* fix: improve REPL stringify logic

* fix: improve REPL stringify logic

* Update sites/svelte-5-preview/src/lib/Output/srcdoc/index.html

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

Author: trueadm

sites/svelte-5-preview/src/lib/Output/srcdoc/index.html

@@ -274,7 +274,22 @@
 
 			function stringify(args) {
 				try {
-					return JSON.stringify(args);
+					return JSON.stringify(args, (key, value) => {
+						// if we don't do this, our Set/Map from svelte/reactivity would show up wrong in the console
+						if (value instanceof Map) {
+							return {
+								type: 'Map',
+								value
+							};
+						}
+						if (value instanceof Set) {
+							return {
+								type: 'Set',
+								value
+							};
+						}
+						return value;
+					});
 				} catch (error) {
 					return null;
 				}