save returns serialised if it doesn't save

Cargo.lock

@@ -1517,7 +1517,7 @@ dependencies = [
 
 [[package]]
 name = "tesla-common"
-version = "0.2.1"
+version = "0.3.0"
 dependencies = [
  "ron",
  "serde",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "tesla-common"
-version = "0.2.1"
+version = "0.3.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

src/lib.rs

@@ -11,9 +11,11 @@ pub struct AuthInfo {
 }
 
 impl AuthInfo {
-    pub fn save(&self, path: &Path) -> Result<(), SaveError> {
-        std::fs::write(path, ron::ser::to_string(self)?)?;
-        Ok(())
+    pub fn save(&self, path: &Path) -> Result<Option<String>, ron::Error> {
+        let ser = ron::ser::to_string(self)?;
+        Ok(std::fs::write(path, ser.clone())
+            .map(|_v| None)
+            .unwrap_or(Some(ser)))
     }
 }