use cached pdf if MWRA returns 404 or something

src/fetch.rs

@@ -1,8 +1,11 @@
-use std::{time::{Duration, Instant, SystemTime}, path::PathBuf};
+use std::{
+    path::PathBuf,
+    time::{Duration, Instant, SystemTime},
+};
 
 use futures::{sink::SinkExt, TryStreamExt};
 use lazy_static::lazy_static;
-use log::info;
+use log::{info, warn};
 use reqwest::Url;
 use scraper::Selector;
 use time::PrimitiveDateTime;
@@ -94,11 +97,9 @@ impl PdfFetcher {
             .ok_or(Error::NotFound)?;
         let pdf_url = CHARTS_URL.join(pdf_href)?;
 
-        let origin_modtime = self
-            .client
-            .head(pdf_url.clone())
-            .send()
-            .await?
+        let head_resp = self.client.head(pdf_url.clone()).send().await?;
+
+        let origin_modtime = head_resp
             .headers()
             .get(reqwest::header::LAST_MODIFIED)
             .and_then(|val| {
@@ -115,7 +116,13 @@ impl PdfFetcher {
             .zip(origin_modtime)
             .map_or(true, |(cache, origin)| origin > cache);
 
-        if outdated {
+        if !head_resp.status().is_success() {
+            warn!(
+                "MWRA server returned unexpected response, not fetching updated PDF: {:?}",
+                head_resp
+            );
+            // Just use the cached PDF, assuming we have it
+        } else if outdated {
             info!("Cached PDF is outdated, downloading latest version");
 
             let mut pdf_stream = self