fix mypy errors

poetry.lock

@@ -597,6 +597,14 @@ virtualenv = ">=16.0.0,<20.0.0 || >20.0.0,<20.0.1 || >20.0.1,<20.0.2 || >20.0.2,
 docs = ["pygments-github-lexers (>=0.0.5)", "sphinx (>=2.0.0)", "sphinxcontrib-autoprogram (>=0.1.5)", "towncrier (>=18.5.0)"]
 testing = ["flaky (>=3.4.0)", "freezegun (>=0.3.11)", "pathlib2 (>=2.3.3)", "psutil (>=5.6.1)", "pytest (>=4.0.0)", "pytest-cov (>=2.5.1)", "pytest-mock (>=1.10.0)", "pytest-randomly (>=1.0.0)"]
 
+[[package]]
+name = "types-markdown"
+version = "3.4.2.1"
+description = "Typing stubs for Markdown"
+category = "main"
+optional = false
+python-versions = "*"
+
 [[package]]
 name = "typing-extensions"
 version = "4.4.0"
@@ -684,7 +692,7 @@ python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,>=2.7"
 [metadata]
 lock-version = "1.1"
 python-versions = "~3.11"
-content-hash = "d26f06a75123eb12e0ad3a77ffa15ead9cd93fd4c7f1ae10ab7d841910805b61"
+content-hash = "94614b000f5848489ed0e32caf25a06df9daa05bc063d0e2fe03a00f6859d27b"
 
 [metadata.files]
 apscheduler = [
@@ -1040,6 +1048,10 @@ tox = [
     {file = "tox-3.27.1-py2.py3-none-any.whl", hash = "sha256:f52ca66eae115fcfef0e77ef81fd107133d295c97c52df337adedb8dfac6ab84"},
     {file = "tox-3.27.1.tar.gz", hash = "sha256:b2a920e35a668cc06942ffd1cf3a4fb221a4d909ca72191fb6d84b0b18a7be04"},
 ]
+types-markdown = [
+    {file = "types-Markdown-3.4.2.1.tar.gz", hash = "sha256:03c0904cf5886a7d8193e2f50bcf842afc89e0ab80f060f389f6c2635c65628f"},
+    {file = "types_Markdown-3.4.2.1-py3-none-any.whl", hash = "sha256:b2333f6f4b8f69af83de359e10a097e4a3f14bbd6d2484e1829d9b0ec56fa0cb"},
+]
 typing-extensions = [
     {file = "typing_extensions-4.4.0-py3-none-any.whl", hash = "sha256:16fa4864408f655d35ec496218b85f79b3437c829e93320c7c9215ccfd92489e"},
     {file = "typing_extensions-4.4.0.tar.gz", hash = "sha256:1511434bb92bf8dd198c12b1cc812e800d4181cfcb867674e0f8279cc93087aa"},

pyproject.toml

@@ -17,6 +17,7 @@ peewee = "^3.14.8"
 tox = "^3.24.5"
 background = "^0.2.1"
 Flask = "^2.1.1"
+types-markdown = "^3.4.2.1"
 
 [tool.poetry.group.dev.dependencies]
 pylint = "^2.15.5"

stacosys/conf/config.py

@@ -44,7 +44,7 @@ class Config:
         section, param = str(key.value).split(".")
         if not param:
             param = section
-            section = None
+            section = ""
         return (section, param)
 
     def exists(self, key: ConfigParameter):