more graceful error handling

src/main.rs

@@ -40,7 +40,7 @@ fn main() -> anyhow::Result<()> {
     let headings = document.select(&headings_selector).map(|a| a.inner_html()).collect::<Vec<_>>();
 
     let heading_selector = scraper::Selector::parse("div#pageContent > h2").unwrap();
-    let album_name = document.select(&heading_selector).next().unwrap().inner_html();
+    let album_name = document.select(&heading_selector).next().context("could not find album name heading")?.inner_html();
 
     for element in document.select(&tracks_selector) {
 
@@ -49,14 +49,30 @@ fn main() -> anyhow::Result<()> {
         tag.set_album(album_name.clone());
 
         let download_link_selector = scraper::Selector::parse("td.playlistDownloadSong > a").unwrap();
-        let download_link = element.select(&download_link_selector).next().unwrap();
+        let download_link = element.select(&download_link_selector).next().context("could not find download link")?;
 
         let columns_selector = scraper::Selector::parse("td").unwrap();
         let columns = element.select(&columns_selector).collect::<Vec<_>>();
-        let track = columns[headings.iter().position(|x| x == "<b>#</b>").unwrap()].inner_html().trim_end_matches(".").parse::<u32>().unwrap();
+        if let Some(track) =
+            headings.iter().position(|x| x == "<b>#</b>")
+            .and_then(|idx| {
+                columns[idx]
+                .inner_html()
+                .trim_end_matches(".")
+                .parse::<u32>().ok()
+            })
+        {
             tag.set_track(track);
-        if let Some(cd) = headings.iter().position(|x| x == "<b>CD</b>") {
+        }
-            tag.set_disc(columns[cd].inner_html().parse::<u32>().unwrap_or(1));
+
+        if let Some(disc) =
+            headings.iter().position(|x| x == "<b>CD</b>").and_then(|idx| {
+                columns[idx]
+                .inner_html()
+                .parse::<u32>().ok()
+            })
+        {
+            tag.set_disc(disc);
         }
 
         let track_url = format!(
@@ -77,7 +93,7 @@ fn main() -> anyhow::Result<()> {
 
         let document = scraper::Html::parse_document(track_page);
         let audio_selector = scraper::Selector::parse("audio").unwrap();
-        let audio = document.select(&audio_selector).next().unwrap();
+        let audio = document.select(&audio_selector).next().context("could not find audio tag")?;
 
         let meta_selector = scraper::Selector::parse("p[align='left'] > b").unwrap();
         let meta = document.select(&meta_selector);
@@ -108,7 +124,7 @@ fn main() -> anyhow::Result<()> {
 
         let mut audio_file = audio_response.as_bytes().to_vec();
 
-        tag.write_to(&mut audio_file, id3::Version::Id3v24).unwrap();
+        tag.write_to(&mut audio_file, id3::Version::Id3v24)?;
 
         fs::write(output.join(sanitize_filename::sanitize(path.as_ref())), audio_response.as_bytes())
             .context("error writing audio file")?;