fix: nil pointer access ( workflow_dispatch )

pkg/runner/testdata/workflow_dispatch-scalar-composite-action/workflow_dispatch.yml

@@ -0,0 +1,17 @@
+name: workflow_dispatch
+
+on: workflow_dispatch
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - run: |
+          runs:
+            using: composite
+            steps:
+            - run: |
+                exit 0
+              shell: bash
+        shell: cp {0} action.yml
+      - uses: ./

pkg/runner/testdata/workflow_dispatch-scalar/workflow_dispatch.yml

@@ -0,0 +1,9 @@
+name: workflow_dispatch
+
+on: workflow_dispatch
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - run: exit 0

pkg/runner/testdata/workflow_dispatch_no_inputs_mapping/workflow_dispatch.yml

@@ -0,0 +1,10 @@
+name: workflow_dispatch
+
+on:
+  workflow_dispatch:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - run: exit 0