Simplify getting the audio data

src/main.rs

@@ -219,19 +219,15 @@ fn ddr2osu(
         .with_context(|| format!("failed to read XWB file {}", &xwb_file.clone().display()))?;
     let wave_bank = WaveBank::parse(&xwb_data).context("failed to parse XWB file")?;
 
-    let audio_data = if wave_bank.sounds.contains_key(&basename) {
-        wave_bank
-            .sounds
-            .get(&basename)
-            .unwrap()
-            .to_wav()
-            .with_context(|| {
+    let audio_data = wave_bank.sounds.get(&basename)
+        .map(|sound| sound.to_wav().with_context(|| {
             format!(
                 "failed to convert wave bank sound entry “{}” to WAV",
                 basename
             )
-            })?
-    } else if wave_bank.sounds.len() == 2 {
+        }))
+        .unwrap_or_else(|| {
+            if wave_bank.sounds.len() == 2 {
                 warn!(
                     "Sound {} not found in wave bank, but it has two entries; assuming these are preview and full song",
                     basename
@@ -243,13 +239,14 @@ fn ddr2osu(
                         "failed to convert wave bank sound entry “{}” to WAV",
                         basename
                     )
-        })?
+                })
             } else {
-        return Err(anyhow!(
+                Err(anyhow!(
                     "Could not find matching sound in wave bank (searched for {})",
                     basename,
-        ));
-    };
+                ))
+            }
+        })?;
 
     let osz = osu::osz::Archive {
         beatmaps,