KeyNotFoundException when pick an icon and then unpick it

[AvihayTWB]

Hi.

First of all- love this package. I use it a lot. thanks.

I get this convertor error:
KeyNotFoundException: The given key '00000000-0000-0000-0000-000000000000' was not present in the dictionary.
System.Collections.Generic.Dictionary<TKey, TValue>.get_Item(TKey key)
Our.Iconic.Core.ValueConverters.IconicValueConverter.ConvertIntermediateToObject(IPublishedElement owner, IPublishedPropertyType propertyType, PropertyCacheLevel referenceCacheLevel, object inter, bool preview)
Umbraco.Cms.Core.Models.PublishedContent.PublishedPropertyType.ConvertInterToObject(IPublishedElement owner, PropertyCacheLevel referenceCacheLevel, object inter, bool preview)
Umbraco.Cms.Core.PublishedCache.PublishedElementPropertyBase.GetValue(string culture, string segment)
Umbraco.Extensions.PublishedPropertyExtension.Value(IPublishedProperty property, IPublishedValueFallback publishedValueFallback, string culture, string segment, Fallback fallback, T defaultValue)
Umbraco.Extensions.PublishedElementExtensions.Value(IPublishedElement content, IPublishedValueFallback publishedValueFallback, string alias, string culture, string segment, Fallback fallback, T defaultValue)
Umbraco.Cms.Web.Common.PublishedModels.MenuItem.get_Icon() in MenuItem.generated.cs

while trying to render an icon for menu items.
If all menu items got an icon - it renders great. But if I unpick one and save I get the error above...
I think it happens only when I pick an icon and then unpick it and save.

seems to be something with the value convertor.
Any Idea for a workaround?