Required fields must also include key

[FlamingFox911]

I ran into a small issue today.

When you have the PropertyFieldPicturePicker property pane in your configuration, it does not mention that a key property is required. So when you build and run it, it will complain saying that the key is undefined. See full error below:

Error: ***The value for "Custom field key" must not be undefined at Function.Validate.isNotNullOrUndefined (sp-loader-assembly_en-us.js:8934) at Function.Validate.isNonemptyString (sp-loader-assembly_en-us.js:8938) at PropertyPaneGroup.webpackJsonp974a7777_0990_4136_8fa6_95d80114c2e0_1_4_1.80.PropertyPaneGroup._renderGroupField (0.sp-webpart-base-propertypane_70d62fbea2076c7f2dde.js:825) at 0.sp-webpart-base-propertypane_70d62fbea2076c7f2dde.js:815 at Array.map (<anonymous>) at PropertyPaneGroup.webpackJsonp974a7777_0990_4136_8fa6_95d80114c2e0_1_4_1.80.PropertyPaneGroup._renderGroupContent (0.sp-webpart-base-propertypane_70d62fbea2076c7f2dde.js:815) at PropertyPaneGroup.webpackJsonp974a7777_0990_4136_8fa6_95d80114c2e0_1_4_1.80.PropertyPaneGroup.render (0.sp-webpart-base-propertypane_70d62fbea2076c7f2dde.js:770) at react-dom.js:5199 at measureLifeCyclePerf (react-dom.js:4479) at ReactCompositeComponentWrapper._renderValidatedComponentWithoutOwnerOrContext (react-dom.js:5198)

Could you please include key as a required field?

Thanks

EDIT: This seems to be occurring in every PropertyField.