LinkML Doc Generator error messages are inconsistent when Range value is prefixed

[mahdanoura]

Describe the bug
I use the following LinkML snippet, which imports hctl and wot_security as local LinkML yaml files.

imports:
  - linkml:types
  - hctl
  - wot_security
classes:
  Thing:
    tree_root: true
    class_uri: td:Thing
    attributes:
      securityDefinitions:
        description: >-
          A security scheme applied to a (set of) affordance(s).
        from_schema: td:hasSecurityConfiguration
        required: true
        multivalued: true
        any_of:
          - range: string
          - range: wot_security:SecuritySchemeType
      links:
        from_schema: td:hasLink
        description: >-
          Provides Web links to arbitrary resources that relate to the specified Thing Description.
        multivalued: true
        range: hctl:Link

I noticed LinkML does not like the prefixing to the imports for specifying the Range. However, the error messages produced are inconsistent. For range: hctl:Link I get the following error:
ValueError: File "thing_description.yaml", line 363, col 16 slot: thing__links - unrecognized range (hctl:Link)

However, for range: wot_security:SecuritySchemeType, the error message is completely vague:
AttributeError: 'NoneType' object has no attribute 'from_schema'

To Reproduce
My environment is as follows:

python = 3.11
linkml-runtime = 1.8.0rc2
linkml = 1.8.0rc2

Expected behavior
I expect the error messages for the same problem to be consistent and meaningful, because digging the issue becomes cumbersome.

Code snippets
I generate the documents using the python class as follows:

doc_generator = DocGenerator('resources/schemas/thing_description.yaml', mergeimports=False)
doc_generator.serialize(directory=str(DOCDIR))

[turbomam]

I agree that LinkML error messages can be confusing and inconsistent.

Is your work in a code repository? Can you share that?

One of the things I wondering about is whether your hctl and wot_security prefixes need to be defined in the schema file that contains the lines you included above.

[mahdanoura]

The code is in this repo and the LinkML schemas are located in the schema directory.
The names I provide in the import statements correspond to the schema names and not their prefixes, otherwise those entities are not found. I appreciate the feedback. Thanks