UPDATE: i misread this error (thought you were referencing the impl class, but really it looks like the HTL cannot instantiate the Sling Model via the interface reference (which is bound to that Impl). See Arun's answer below.
You are trying to access an INTERNAL class as denoted by the "internal" package name: com.adobe.cq.wcm.core.components.internal.models.v1.ExperienceFragmentImpl
Classes under internal packages are considered internal implementation details of the project and cannot be used by Consumer code.
In AEM development, typically you will have public interfaces you can code against, but the implementation (usually post-fixed with Impl) will not be exported by the bundle therefore not available for you to directly use.
As per the error, please check if the core project is installed and resolved in your instance. The issue is regarding the "com.adobe.cq.wcm.core.components.internal.models.v1.ExperienceFragmentImpl" model here.