Fix possible null reference and initialize selected area if empty.

Author: cowmanjoe

Source/Plugins/Tilemaps/Editor/CamViewStates/TilemapEditorCamViewState.cs

@@ -609,6 +609,7 @@ private void DeselectToolInInspector()
 		private void MoveTilePaletteSelection(Keys keyPressed)
 		{
 			TilemapToolSourcePalette sourcePalette = TilemapsEditorPlugin.Instance.PeekTilePalette();
+			if (sourcePalette == null) return;
 
 			if (keyPressed == Keys.Up)
 			{
@@ -630,6 +631,7 @@ private void MoveTilePaletteSelection(Keys keyPressed)
 		private void ExpandTilePaletteSelection(Keys keyPressed)
 		{
 			TilemapToolSourcePalette sourcePalette = TilemapsEditorPlugin.Instance.PeekTilePalette();
+			if (sourcePalette == null) return;
 
 			if (keyPressed == Keys.Up)
 			{
@@ -651,6 +653,7 @@ private void ExpandTilePaletteSelection(Keys keyPressed)
 		private void ShrinkTilePaletteSelection(Keys keyPressed)
 		{
 			TilemapToolSourcePalette sourcePalette = TilemapsEditorPlugin.Instance.PeekTilePalette();
+			if (sourcePalette == null) return;
 
 			if (keyPressed == Keys.Up)
 			{

Source/Plugins/Tilemaps/Editor/Modules/SourcePaletteTilesetView.cs

@@ -78,6 +78,12 @@ public IReadOnlyGrid<Tile> SelectedTiles
 		}
 		internal void TranslateSelectedArea(int offsetX, int offsetY)
 		{
+			if (this.selectedArea.IsEmpty)
+			{
+				this.InitializeSelectedArea();
+				return;
+			}
+
 			int newX = MathF.Clamp(this.selectedArea.X + offsetX, 0, this.DisplayedTileCount.X - this.selectedArea.Width);
 			int newY = MathF.Clamp(this.selectedArea.Y + offsetY, 0, this.DisplayedTileCount.Y - this.selectedArea.Height);
 
@@ -87,6 +93,12 @@ internal void TranslateSelectedArea(int offsetX, int offsetY)
 		}
 		internal void ExpandSelectedArea(int diffX, int diffY)
 		{
+			if (this.selectedArea.IsEmpty)
+			{
+				this.InitializeSelectedArea();
+				return;
+			}
+
 			int newX = MathF.Max(this.selectedArea.X + MathF.Min(diffX, 0), 0);
 			int newY = MathF.Max(this.selectedArea.Y + MathF.Min(diffY, 0), 0);
 
@@ -104,6 +116,12 @@ internal void ExpandSelectedArea(int diffX, int diffY)
 		}
 		public void ShrinkSelectedArea(int diffX, int diffY)
 		{
+			if (this.selectedArea.IsEmpty)
+			{
+				this.InitializeSelectedArea();
+				return;
+			}
+
 			int newX = MathF.Min(this.selectedArea.X + MathF.Max(diffX, 0),
 				this.selectedArea.X + this.selectedArea.Width - 1);
 			int newY = MathF.Min(this.selectedArea.Y + MathF.Max(diffY, 0),
@@ -483,6 +501,12 @@ private void UpdateSelectedTiles()
 				}
 			}
 		}
+		private void InitializeSelectedArea()
+		{
+			Rectangle rect = new Rectangle(0, 0, 1, 1);
+			this.SelectedArea = rect;
+			this.RaiseSelectedAreaEditingFinished();
+		}
 
 		private void RaiseSelectedAreaEditingFinished()
 		{

Source/Plugins/Tilemaps/Editor/Modules/TilemapToolSourcePalette.cs

@@ -45,7 +45,7 @@ public TilemapToolSourcePalette()
 		}
 
 		/// <summary>
-		/// Translates the selected area in the source palette by a number of tiles in the X and Y axes.
+		/// Translates the selected area in the source palette by a number of tiles along the X and Y axes.
 		/// </summary>
 		public void TranslateSelectedArea(int offsetX, int offsetY)
 		{