fix crash (#1826)

HMCL/src/main/java/moe/mickey/minecraft/skin/fx/SkinCanvas.java

@@ -16,8 +16,8 @@ import org.jetbrains.annotations.Nullable;
 
 public class SkinCanvas extends Group {
 
-    public static final Image ALEX = new Image(SkinCanvas.class.getResourceAsStream("/assets/img/alex.png"));
-    public static final Image STEVE = new Image(SkinCanvas.class.getResourceAsStream("/assets/img/steve.png"));
+    public static final Image ALEX = new Image(SkinCanvas.class.getResourceAsStream("/assets/img/skin/alex.png"));
+    public static final Image STEVE = new Image(SkinCanvas.class.getResourceAsStream("/assets/img/skin/steve.png"));
 
     public static final SkinCube ALEX_LARM = new SkinCube(3, 12, 4, 14F / 64F, 16F / 64F, 32F / 64F, 48F / 64F, 0F, true);
     public static final SkinCube ALEX_RARM = new SkinCube(3, 12, 4, 14F / 64F, 16F / 64F, 40F / 64F, 16F / 64F, 0F, true);

HMCL/src/main/java/org/jackhuang/hmcl/game/TexturesLoader.java

@@ -136,8 +136,8 @@ public final class TexturesLoader {
     private final static Map<TextureModel, LoadedTexture> DEFAULT_SKINS = new EnumMap<>(TextureModel.class);
 
     static {
-        loadDefaultSkin("/assets/img/steve.png", TextureModel.STEVE);
-        loadDefaultSkin("/assets/img/alex.png", TextureModel.ALEX);
+        loadDefaultSkin("/assets/img/skin/steve.png", TextureModel.STEVE);
+        loadDefaultSkin("/assets/img/skin/alex.png", TextureModel.ALEX);
     }
 
     private static void loadDefaultSkin(String path, TextureModel model) {

HMCL/src/main/java/org/jackhuang/hmcl/ui/main/MainPage.java

@@ -29,13 +29,9 @@ import javafx.collections.ObservableList;
 import javafx.geometry.Insets;
 import javafx.geometry.Pos;
 import javafx.scene.Node;
-import javafx.scene.SnapshotParameters;
-import javafx.scene.canvas.Canvas;
-import javafx.scene.canvas.GraphicsContext;
 import javafx.scene.control.Label;
 import javafx.scene.image.Image;
 import javafx.scene.image.ImageView;
-import javafx.scene.image.WritableImage;
 import javafx.scene.layout.HBox;
 import javafx.scene.layout.StackPane;
 import javafx.scene.layout.VBox;