Fix synchronize return on fail

Author: jpenilla

src/main/java/ca/spottedleaf/moonrise/mixin/chunk_system/ChunkMapMixin.java

@@ -617,8 +617,12 @@ public CompletableFuture<Void> write(final ChunkPos pos, final Supplier<Compound
 
     @Override
     public CompletableFuture<Void> synchronize(boolean flush) {
-        MoonriseRegionFileIO.flush(this.level);
-        return CompletableFuture.completedFuture(null);
+        try {
+            MoonriseRegionFileIO.flush(this.level);
+            return CompletableFuture.completedFuture(null);
+        } catch (final Exception ex) {
+            return CompletableFuture.failedFuture(ex);
+        }
     }
 
     /**

src/main/java/ca/spottedleaf/moonrise/mixin/chunk_system/SimpleRegionStorageMixin.java

@@ -158,10 +158,11 @@ private void synchroniseLegacyDataWrite(final LegacyTagFixer instance, final Chu
     public CompletableFuture<Void> synchronize(boolean flush) {
         try {
             this.storage.flush();
+            return CompletableFuture.completedFuture(null);
         } catch (final IOException ex) {
             LOGGER.error("Failed to flush chunk storage", ex);
+            return CompletableFuture.failedFuture(ex);
         }
-        return CompletableFuture.completedFuture(null);
     }
 
     /**