Fix createBorderRadiusArr

[rosco54]

Function createBorderRadiusArr() failed if no series are defined, eg when data series are expected to be loaded later via the update call. Two samples (axios and jquery) were failing during npm run e2e

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• My branch is up to date with any changes from the main branch