fix(isColorString): cannot convert undefined or null to object

[kurtextrem]

The current line breaks if the v is null or undefined. TS does not catch it, as Object.prototype.hasOwnProperty.call takes in args of type any (which v is). I assume the type is wrong and should be Exclude<undefined | null, any> instead (but that's a TS issue)

[iRevolutionDev]

Waiting for this fix!!