bug: showStipes breaks clustering when showStipes = false

[Async0x42]

#276 breaks clustering when showStipes is false. Using the example page, if you disable showStipes, it throws an exception because the dot/line don't exist.

https://codepen.io/Async0x42/pen/RwPQYvY?editable=true

ClusterItem.js:542 Uncaught TypeError: Cannot read property 'offsetHeight' of undefined
at e.value (ClusterItem.js:542)
at e.o (ClusterItem.js:109)
at Group.js:1126
at Object.forEach (vis-util.js:38)
at t.value (Group.js:1125)
at p (Group.js:378)
at t.value (Group.js:422)
at Array.r (Group.js:533)
at ItemSet.js:837
at Object.forEach (vis-util.js:38)

[vis-bot]

🎉 This issue has been resolved in version 7.3.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀