Versions
WorldEdit version: 7.2.0-SNAPSHOT (build #5394)
Platform version: git-Paper-204 (MC: 1.16.3)

Describe the bug
Set block change limit to -1 (//limit -1) and you won't be able to cut/copy anything.

To Reproduce

1. Select an area
2. Try to copy or cut
3. WorldEdit tells you off

Expected behavior
WorldEdit should special case -1 as limit value.

Additional context
Bug was introduced in PR #1536, fd8dbdd#diff-1f76533288bba727d414767ce2e1abb9R79