Fix current Rust clippy findings

crates/pdf/src/export.rs

@@ -203,7 +203,7 @@ impl GreyImage {
             return None;
         }
         let (mut grey, mut alpha) = (Vec::with_capacity(pixels), Vec::with_capacity(pixels));
-        for p in img.data().chunks_exact(2) {
+        for p in img.data().as_chunks::<2>().0 {
             grey.push(p[0]);
             alpha.push(p[1]);
         }

crates/render/src/lib.rs

@@ -72,19 +72,18 @@ impl Rendered {
     }
     /// PNG bytes (empty, with the error logged, if the image can't be encoded).
     pub fn to_png(&self) -> Vec<u8> {
-        let mut buf = Vec::new();
         let mut px = self.to_straight();
         // `pixels` is public: a mismatched buffer is padded or cut to the stated size.
         px.resize(self.width as usize * self.height as usize * 4, 0);
         let Ok(img) = craft_image_codecs::Image::from_u8(self.width, self.height, craft_image_codecs::ChannelLayout::Rgba, px) else {
             log::error!("PNG encode: {}×{} image is too large", self.width, self.height);
-            return buf;
+            return Vec::new();
         };
         match craft_image_codecs::encode(&img, craft_image_codecs::Format::Png, &Default::default()) {
             Ok(bytes) => bytes,
             Err(e) => {
                 log::error!("PNG encode: {e}");
-                buf
+                Vec::new()
             }
         }
     }
@@ -100,17 +99,16 @@ impl Rendered {
                 [mix(p[0]), mix(p[1]), mix(p[2])]
             })
             .collect();
-        let mut buf = Vec::new();
         let Ok(img) = craft_image_codecs::Image::from_u8(self.width, self.height, craft_image_codecs::ChannelLayout::Rgb, rgb) else {
             log::error!("JPEG encode: {}×{} image is too large", self.width, self.height);
-            return buf;
+            return Vec::new();
         };
         let options = craft_image_codecs::EncodeOptions { jpeg_quality: quality.clamp(1, 100), ..Default::default() };
         match craft_image_codecs::encode(&img, craft_image_codecs::Format::Jpeg, &options) {
             Ok(bytes) => bytes,
             Err(e) => {
                 log::error!("JPEG encode: {e}");
-                buf
+                Vec::new()
             }
         }
     }