Remove ? for pixelMap and paletteOwner

src/ImageSharp/Processing/Processors/Quantization/OctreeQuantizer{TPixel}.cs

@@ -26,7 +26,7 @@ public struct OctreeQuantizer<TPixel> : IQuantizer<TPixel>
     private readonly int maxColors;
     private readonly int bitDepth;
     private readonly Octree octree;
-    private IMemoryOwner<TPixel>? paletteOwner;
+    private IMemoryOwner<TPixel> paletteOwner;
     private ReadOnlyMemory<TPixel> palette;
     private EuclideanPixelMap<TPixel>? pixelMap;
     private readonly bool isDithering;
@@ -98,7 +98,7 @@ public struct OctreeQuantizer<TPixel> : IQuantizer<TPixel>
         }
 
         int paletteIndex = 0;
-        Span<TPixel> paletteSpan = this.paletteOwner!.GetSpan();
+        Span<TPixel> paletteSpan = this.paletteOwner.GetSpan();
 
         // On very rare occasions, (blur.png), the quantizer does not preserve a
         // transparent entry when palletizing the captured colors.
@@ -112,7 +112,7 @@ public struct OctreeQuantizer<TPixel> : IQuantizer<TPixel>
         }
 
         this.octree.Palletize(paletteSpan, max, ref paletteIndex);
-        ReadOnlyMemory<TPixel> result = this.paletteOwner!.Memory[..paletteSpan.Length];
+        ReadOnlyMemory<TPixel> result = this.paletteOwner.Memory[..paletteSpan.Length];
 
         // When called multiple times by QuantizerUtilities.BuildPalette
         // this prevents memory churn caused by reallocation.
@@ -157,8 +157,7 @@ public struct OctreeQuantizer<TPixel> : IQuantizer<TPixel>
         if (!this.isDisposed)
         {
             this.isDisposed = true;
-            this.paletteOwner?.Dispose();
-            this.paletteOwner = null;
+            this.paletteOwner.Dispose();
             this.pixelMap?.Dispose();
             this.pixelMap = null;
         }

src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer{TPixel}.cs

@@ -20,7 +20,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization;
 internal struct PaletteQuantizer<TPixel> : IQuantizer<TPixel>
     where TPixel : unmanaged, IPixel<TPixel>
 {
-    private EuclideanPixelMap<TPixel>? pixelMap;
+    private EuclideanPixelMap<TPixel> pixelMap;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="PaletteQuantizer{TPixel}"/> struct.
@@ -46,7 +46,7 @@ internal struct PaletteQuantizer<TPixel> : IQuantizer<TPixel>
     public QuantizerOptions Options { get; }
 
     /// <inheritdoc/>
-    public ReadOnlyMemory<TPixel> Palette => this.pixelMap!.Palette;
+    public ReadOnlyMemory<TPixel> Palette => this.pixelMap.Palette;
 
     /// <inheritdoc/>
     [MethodImpl(InliningOptions.ShortMethod)]
@@ -62,12 +62,11 @@ internal struct PaletteQuantizer<TPixel> : IQuantizer<TPixel>
     /// <inheritdoc/>
     [MethodImpl(InliningOptions.ShortMethod)]
     public readonly byte GetQuantizedColor(TPixel color, out TPixel match)
-        => (byte)this.pixelMap!.GetClosestColor(color, out match);
+        => (byte)this.pixelMap.GetClosestColor(color, out match);
 
     /// <inheritdoc/>
     public void Dispose()
     {
-        this.pixelMap?.Dispose();
-        this.pixelMap = null;
+        this.pixelMap.Dispose();
     }
 }