fix: only write IP cache after API call

previously, when the API call would fail (for whatever reason),
the cached IP had already been written, so following executions
wouldn't attempt to update the IP, even though the previous
attempt had failed.

src/main.rs

@@ -62,15 +62,6 @@ fn main() -> Result<()> {
         return Ok(());
     }
 
-    if should_use_cache {
-        println!(
-            "Saving current IP {} to cache file {:?}...",
-            &current_ip,
-            &args.cache.clone().unwrap()
-        );
-        write_file(&args.cache.unwrap(), &current_ip)?;
-    }
-
     let (api_token, zone, domain) = match args.config {
         Some(c) => {
             let config_str = read_file(&c)?;
@@ -91,6 +82,15 @@ fn main() -> Result<()> {
         &domain, &current_ip
     );
 
+    if should_use_cache {
+        println!(
+            "Saving current IP {} to cache file {:?}...",
+            &current_ip,
+            &args.cache.clone().unwrap()
+        );
+        write_file(&args.cache.unwrap(), &current_ip)?;
+    }
+
     Ok(())
 }