Merge branch 'pulls/1195352/8'

(cherry picked from commit c9cccf9eb2)

.idea/misc.xml

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ProjectRootManager" version="2" default="true" />
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="21" project-jdk-type="JavaSDK" />
 </project>

hacked-libtiled/tiled/core/TileSet.java

@@ -98,7 +98,11 @@ public class TileSet implements Iterable<Tile>
         
         File f = new File(imgFilename);
 
-        BufferedImage image = ImageIO.read(f.getCanonicalFile());
+        BufferedImage image;
+        try {
+            image = ImageIO.read(f.getCanonicalFile());
+        } catch (IOException e) { throw new IOException("Failed to load " + imgFilename);
+        }
         if (image == null) {
             throw new IOException("Failed to load " + imgFilename);
         }

src/com/gpl/rpg/atcontentstudio/model/gamedata/NPC.java

@@ -333,6 +333,10 @@ public class NPC extends JSONElement {
 		}
 		if (this.icon_id != null) {
 			String spritesheetId = this.icon_id.split(":")[0];
+			if (proj.getSpritesheet(spritesheetId) == null) {
+				Notification.addError("Error Spritesheet "+id+". has no backlink.");
+				return;
+			}
 			proj.getSpritesheet(spritesheetId).addBacklink(this);
 		}