bugfix #4767 Get 'NaN' in tooltip of Timeline Series. Get 'undefined'…

[cuobiezi]

… at tooltip.y.formatter first arguments

New Pull Request

Bugfix #4767 Get 'NaN' in tooltip of Timeline Series. Get 'undefined' at tooltip.y.formatter first arguments
Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)
#4767

Type of change

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• 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
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• My branch is up to date with any changes from the main branch