fix: clamp file offsets to file size

src/mpd_encoder.rs

@@ -145,7 +145,7 @@ impl MpdEncoder {
             };
 
             let mip_size = if next == 0 {
-                size as u32 - offset
+                size as u32 - offset.min(size as u32)
             } else {
                 next - offset
             };