Batch mode crashes in latexpdf target

[ailin-nemui]

Hi, I wanted to try the batch mode so I set plantuml_batch_size in conf.py

Then I get this error:

writing... rendering plantuml diagrams [0..9/9]... failed
failed

Exception occurred:
  File "sphinxcontrib/plantuml.py", line 320, in _render_files
    cmdargs.extend(_ARGS_BY_FILEFORMAT[fileformat])
KeyError: 'pdf'

# Sphinx version: 3.5.3
# Python version: 3.8.5 (CPython)
# Docutils version: 0.16 release
# Jinja2 version: 2.11.3
# Last messages:
#   source/owlapy.render
#   source/owlapy.utils
#   source/owlapy.vocabulary
#   
#   resolving references...
#   done
#   writing...
#   rendering plantuml diagrams [0..9/9]...
#   failed
#   failed
# Loaded extensions:
#   sphinx.ext.mathjax (3.5.3) from sphinx/ext/mathjax.py
#   sphinxcontrib.applehelp (1.0.2) from sphinxcontrib/applehelp/__init__.py
#   sphinxcontrib.devhelp (1.0.2) from sphinxcontrib/devhelp/__init__.py
#   sphinxcontrib.htmlhelp (1.0.3) from sphinxcontrib/htmlhelp/__init__.py
#   sphinxcontrib.serializinghtml (1.1.4) from sphinxcontrib/serializinghtml/__init__.py
#   sphinxcontrib.qthelp (1.0.3) from sphinxcontrib/qthelp/__init__.py
#   alabaster (0.7.12) from alabaster/__init__.py
#   sphinx.ext.githubpages (3.5.3) from sphinx/ext/githubpages.py
#   sphinx.ext.autodoc.type_comment (3.5.3) from sphinx/ext/autodoc/type_comment.py
#   sphinx.ext.autodoc (3.5.3) from sphinx/ext/autodoc/__init__.py
#   sphinx.ext.napoleon (3.5.3) from sphinx/ext/napoleon/__init__.py
#   sphinx.ext.viewcode (3.5.3) from sphinx/ext/viewcode.py
#   sphinxcontrib.plantuml (unknown version) from sphinxcontrib/plantuml.py
#   myst_parser (0.13.5) from myst_parser/__init__.py
Traceback (most recent call last):
  File "sphinx/cmd/build.py", line 280, in build_main
    app.build(args.force_all, filenames)
  File "sphinx/application.py", line 352, in build
    self.builder.build_update()
  File "sphinx/builders/__init__.py", line 293, in build_update
    self.build(['__all__'], to_build)
  File "sphinx/builders/__init__.py", line 360, in build
    self.write(docnames, list(updated_docnames), method)
  File "sphinx/builders/latex/__init__.py", line 304, in write
    docwriter.write(doctree, destination)
  File "docutils/writers/__init__.py", line 78, in write
    self.translate()
  File "sphinx/writers/latex.py", line 101, in translate
    self.document.walkabout(visitor)
  File "docutils/nodes.py", line 214, in walkabout
    if child.walkabout(visitor):
  File "docutils/nodes.py", line 214, in walkabout
    if child.walkabout(visitor):
  File "docutils/nodes.py", line 214, in walkabout
    if child.walkabout(visitor):
  [Previous line repeated 3 more times]
  File "docutils/nodes.py", line 206, in walkabout
    visitor.dispatch_visit(self)
  File "sphinx/util/docutils.py", line 468, in dispatch_visit
    method(node)
  File "sphinxcontrib/plantuml.py", line 558, in latex_visit_plantuml
    _render_batches_on_vist(self)
  File "sphinxcontrib/plantuml.py", line 371, in _render_batches_on_vist
    self.builder.plantuml_builder.render_batches()
  File "sphinxcontrib/plantuml.py", line 314, in render_batches
    self._render_files(keys, fileformat)
  File "sphinxcontrib/plantuml.py", line 320, in _render_files
    cmdargs.extend(_ARGS_BY_FILEFORMAT[fileformat])
KeyError: 'pdf'

Thanks