Property context '{0}.{1}' already set to '{2}', cannot override to '{3}'.
This error occurs when the security context for a property is defined via addPropertySecurityContext() multiple times under different security contexts.
For example:
$compileProvider.addPropertySecurityContext("my-element", "src", $sce.MEDIA_URL);
$compileProvider.addPropertySecurityContext("my-element", "src", $sce.RESOURCE_URL); //throws