Can't find factory for 'scispacy_linker' for language English

[zhanyuanucb]

Describe the bug ValueError: [E002] Can't find factory for 'scispacy_linker' for language English occurs if one doesn't import scispacy.linking

To Reproduce Steps to reproduce the behavior:

import spacy

lang_model = "en_core_sci_sm"
nlp = spacy.load(lang_model)
nlp.add_pipe("scispacy_linker",
             config={"resolve_abbreviations": True,
                     "linker_name": "umls"})

Environment (please complete the following information):

• OS: Ubuntu 16.04
• Version:

  >>> scispacy.__version__
  '0.4.0'
  >>> spacy.__version__
  '3.0.7'

• Python: python3.6

[dakinggg]

This is the expected behavior, the import statement is necessary.