[BUGFIX] Colorpicker in irre records

This patch checks if a value is set before writing
a possbile empty value to the field.

Resolves: #83000
Releases: master, 8.7
Change-Id: I3badd9b9ff1a567351d971b5ae0199bf347e0f72
Reviewed-on: https://review.typo3.org/54731


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Jan Helke <typo3@helke.de>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>