Clustering no longer works when assigning a label to datasource entities

Description

dataSourcePromise.then(function (dataSource) {
  for (const source of dataSource.entities.values) {
    source.label = {
      text: ''
    }
  }
  ...
})

Contributor guide

Tech stack

javascript

Domain

frontend

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

fresh

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

Familiarity with CesiumJSBasic JavaScriptKnowledge of clustering in Cesium

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

60

Research direction

The issue is reproducible via the provided Sandcastle example. The bug occurs when assigning a label with an empty string to a datasource entity. Likely a missing null/empty check in the clustering logic. Investigate files like `Source/DataSources/EntityCluster.js` and `Source/Scene/PointPrimitiveCluster.js` for how labels are handled during clustering. Check if there is an existing test for this scenario. The fix might involve ignoring labels with empty text during cluster calculation or ensuring they don't break the clustering process.