Fix exception related to include_tasks

Fixes: #2875

.github/workflows/tox.yml

@@ -70,7 +70,7 @@ jobs:
       WSLENV: FORCE_COLOR:PYTEST_REQPASS:TOXENV:GITHUB_STEP_SUMMARY
       # Number of expected test passes, safety measure for accidental skip of
       # tests. Update value if you add/remove tests.
-      PYTEST_REQPASS: 774
+      PYTEST_REQPASS: 775
 
     steps:
       - name: Activate WSL1

examples/playbooks/tasks/bug-2875.yml

@@ -0,0 +1,8 @@
+- name: "Reproduce bug #2875"
+  include_tasks: "{{ lookup('first_found', __ff_params) }}"
+  vars:
+    __ff_params:
+      files:
+        - "default.yml"
+      paths:
+        - "{{ role_path }}/tasks/setup"

src/ansiblelint/utils.py

@@ -315,7 +315,7 @@ def _include_children(
         v = v["file"]
 
     # we cannot really parse any jinja2 in includes, so we ignore them
-    if "{{" in v:  # pragma: no branch
+    if not v or "{{" in v:
         return []
 
     if "import_playbook" in k and COLLECTION_PLAY_RE.match(v):

test/test_utils.py

@@ -39,6 +39,7 @@
 from ansiblelint.cli import get_rules_dirs
 from ansiblelint.constants import VIOLATIONS_FOUND_RC
 from ansiblelint.file_utils import Lintable
+from ansiblelint.runner import Runner
 
 runtime = Runtime(require_module=True)
 
@@ -390,3 +391,11 @@ def test_nested_items() -> None:
 def test_find_children() -> None:
     """Verify correct function of find_children()."""
     utils.find_children(Lintable("examples/playbooks/find_children.yml"))
+
+
+def test_find_children_in_task(default_rules_collection) -> None:
+    """Verify correct function of find_children() in tasks."""
+    Runner(
+        Lintable("examples/playbooks/tasks/bug-2875.yml"),
+        rules=default_rules_collection,
+    ).run()