fix another edge case

src/actions-util.test.ts

@@ -285,6 +285,20 @@ test("validateWorkflow() for a range of malformed workflows", (t) => {
   t.deepEqual(actionsutil.validateWorkflow(1 as any), [
     actionsutil.WorkflowErrors.MissingHooks,
   ]);
+
+  t.deepEqual(
+    actionsutil.validateWorkflow({
+      on: {
+        push: {
+          branches: 1,
+        },
+        pull_request: {
+          branches: 1,
+        },
+      },
+    } as any),
+    []
+  );
 });
 
 test("validateWorkflow() when on.pull_request for every branch but push specifies branches", (t) => {

src/actions-util.ts

@@ -168,10 +168,13 @@ function branchesToArray(branches?: string | null | string[]): string[] | "**" {
   if (typeof branches === "string") {
     return [branches];
   }
-  if (!branches || branches.length === 0) {
-    return "**";
+  if (Array.isArray(branches)) {
+    if (branches.length === 0) {
+      return "**";
+    }
+    return branches;
   }
-  return branches;
+  return "**";
 }
 
 enum MissingTriggers {