fix autofmt: don't panic when writing blocks out without a srcfile (#2854)

* fix: don't panic when writing blocks out
* also fix serialization for hotreload
* fix windows line endings

packages/autofmt/tests/srcless.rs

@@ -0,0 +1,21 @@
+use dioxus_rsx::CallBody;
+use proc_macro2::TokenStream as TokenStream2;
+
+/// Ensure we can write RSX blocks without a source file
+///
+/// Useful in code generation use cases where we still want formatted code.
+#[test]
+fn write_block_out() {
+    let src = include_str!("./srcless/basic_expr.rsx");
+
+    let tokens: TokenStream2 = syn::parse_str(src).unwrap();
+    let parsed: CallBody = syn::parse2(tokens).unwrap();
+
+    let block = dioxus_autofmt::write_block_out(&parsed).unwrap();
+
+    // normalize line endings for windows tests to pass
+    pretty_assertions::assert_eq!(
+        block.trim().lines().collect::<Vec<_>>().join("\n"),
+        src.trim().lines().collect::<Vec<_>>().join("\n")
+    );
+}