Fix mypy errors in core.py (#150)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: dcherian <deepak@cherian.net>

.github/workflows/ci-additional.yaml

@@ -73,46 +73,46 @@ jobs:
         run: |
           python -m pytest --doctest-modules flox --ignore flox/tests
 
-  # mypy:
-    # name: Mypy
-    # runs-on: "ubuntu-latest"
-    # needs: detect-ci-trigger
-    # if: needs.detect-ci-trigger.outputs.triggered == 'false'
-    # defaults:
-      # run:
-        # shell: bash -l {0}
-    # env:
-      # CONDA_ENV_FILE: ci/environment.yml
-      # PYTHON_VERSION: "3.10"
+  mypy:
+    name: Mypy
+    runs-on: "ubuntu-latest"
+    needs: detect-ci-trigger
+    if: needs.detect-ci-trigger.outputs.triggered == 'false'
+    defaults:
+      run:
+        shell: bash -l {0}
+    env:
+      CONDA_ENV_FILE: ci/environment.yml
+      PYTHON_VERSION: "3.10"
 
-    # steps:
-      # - uses: actions/checkout@v3
-        # with:
-          # fetch-depth: 0 # Fetch all history for all branches and tags.
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0 # Fetch all history for all branches and tags.
 
-      # - name: set environment variables
-        # run: |
-          # echo "TODAY=$(date +'%Y-%m-%d')" >> $GITHUB_ENV
-      # - name: Setup micromamba
-        # uses: mamba-org/provision-with-micromamba@34071ca7df4983ccd272ed0d3625818b27b70dcc
-        # with:
-          # environment-file: ${{env.CONDA_ENV_FILE}}
-          # environment-name: xarray-tests
-          # extra-specs: |
-            # python=${{env.PYTHON_VERSION}}
-          # cache-env: true
-          # cache-env-key: "${{runner.os}}-${{runner.arch}}-py${{env.PYTHON_VERSION}}-${{env.TODAY}}-${{hashFiles(env.CONDA_ENV_FILE)}}"
-      # - name: Install xarray
-        # run: |
-          # python -m pip install --no-deps -e .
-      # - name: Version info
-        # run: |
-          # conda info -a
-          # conda list
-      # - name: Install mypy
-        # run: |
-          # python -m pip install mypy
+      - name: set environment variables
+        run: |
+          echo "TODAY=$(date +'%Y-%m-%d')" >> $GITHUB_ENV
+      - name: Setup micromamba
+        uses: mamba-org/provision-with-micromamba@34071ca7df4983ccd272ed0d3625818b27b70dcc
+        with:
+          environment-file: ${{env.CONDA_ENV_FILE}}
+          environment-name: xarray-tests
+          extra-specs: |
+            python=${{env.PYTHON_VERSION}}
+          cache-env: true
+          cache-env-key: "${{runner.os}}-${{runner.arch}}-py${{env.PYTHON_VERSION}}-${{env.TODAY}}-${{hashFiles(env.CONDA_ENV_FILE)}}"
+      - name: Install xarray
+        run: |
+          python -m pip install --no-deps -e .
+      - name: Version info
+        run: |
+          conda info -a
+          conda list
+      - name: Install mypy
+        run: |
+          python -m pip install mypy
 
-      # - name: Run mypy
-        # run: |
-          # python -m mypy --install-types --non-interactive
+      - name: Run mypy
+        run: |
+          python -m mypy --install-types --non-interactive

flox/aggregations.py

@@ -467,7 +467,7 @@ def _initialize_aggregation(
     func: str | Aggregation,
     array_dtype,
     fill_value,
-    min_count: int,
+    min_count: int | None,
     finalize_kwargs,
 ) -> Aggregation:
     if not isinstance(func, Aggregation):