fix FastSchematicReaderV3 throwing / by 0 for 1-wide/long schematics (#3360)

fix divide by zero issue

Author: ZECHEESELORD

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/clipboard/io/FastSchematicReaderV3.java

@@ -175,7 +175,7 @@ public Clipboard read(final UUID uuid, final Function<BlockVector3, Clipboard> c
                 default -> this.nbtInputStream.readTagPayloadLazy(type, 0);
             }
             if (clipboard == null && this.areDimensionsAvailable()) {
-                clipboard = createOutput.apply(this.dimensions);
+                clipboard = createOutput.apply(this.dimensions.toImmutable());
             }
         }