fix: preserve scheduler save IOException propagation

src/main/scala/codechicken/multipart/TickScheduler.java

@@ -183,7 +183,7 @@ public final class TickScheduler {
                 CompressedStreamTools.writeCompressed(saveTag(), dout);
                 dout.close();
             } catch (java.io.IOException e) {
-                throw new RuntimeException(e);
+                throw TickScheduler.<RuntimeException>rethrow(e);
             }
         }
 
@@ -316,6 +316,11 @@ public final class TickScheduler {
         return new WorldTickScheduler(world);
     }
 
+    @SuppressWarnings("unchecked")
+    private static <T extends Throwable> RuntimeException rethrow(Throwable throwable) throws T {
+        throw (T) throwable;
+    }
+
     public static ChunkExtension createChunkExtension(Chunk chunk, WorldExtension world) {
         return new ChunkTickScheduler(chunk, (WorldTickScheduler) world);
     }

src/test/java/codechicken/multipart/TickSchedulerSaveFailureRegressionTest.java

@@ -0,0 +1,25 @@
+package codechicken.multipart;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class TickSchedulerSaveFailureRegressionTest {
+
+    @Test
+    void savePropagatesTheOriginalIoException(@TempDir Path directory) {
+        TickScheduler.WorldTickScheduler scheduler = new TickScheduler.WorldTickScheduler(null) {
+
+            @Override
+            File saveFile() {
+                return directory.toFile();
+            }
+        };
+        assertThrows(IOException.class, scheduler::save);
+    }
+}