Add length assertion

src/lib.rs

@@ -122,6 +122,7 @@ impl Encoder {
             for (ComponentState { x, y, .. }, rgb) in self.factors.iter_mut() {
                 let basis = f32::cos(*x as f32 * scale_x) * f32::cos(*y as f32 * scale_y);
 
+                assert_eq!(chunk.len(), rgb.len());
                 for (val, slot) in chunk
                     .iter()
                     .map(|byte| basis * srgb_to_linear(*byte))
@@ -168,7 +169,7 @@ impl Encoder {
             }
         }
 
-        let mut blurhash = String::new();
+        let mut blurhash = String::with_capacity(30);
 
         let (_, dc) = self.factors[0];
         let ac = &self.factors[1..];