Using themeColor when setting color prop on Icon results in console error

[sushitommy]

Describe the bug
Using the themeColor util when setting the color prop on an Icon results in a console error:
Invalid value for prop color on <span> tag. Either remove it from the element, or pass a string or number value to keep it in the DOM. For details, see https://fb.me/react-attribute-behavior

To Reproduce
Steps to reproduce the behavior:

1. Put an Icon component inside your React app and use themeColor to set the color: <Icon size={14} color={themeColor('tint', 'level5')}>

Expected behavior
The color of the icon should be set without any problem (as described in the storybook docs)

Desktop (please complete the following information):

• OS: OSX
• Browser: Chrome

Additional context
The color prop does not show in the DOM. It seems that themeColor the function does not parse correctly to a string, so the value of the prop is invalid. It is fixable by fetching the styled-components theme context, wrap it in an object and call the themeColor function like
const themeContext = { theme: useContext(ThemeContext) as Theme.ThemeInterface };
and then
<Icon size={14} color={themeColor('tint', 'level5')(themeContext)} />