fix: Handle location header array with a single value without emitting warning

Co-authored with @brunns
Related to opennextjs#977

Author: donnabelsey

packages/open-next/src/http/util.ts

@@ -23,7 +23,7 @@ export const parseHeaders = (
      * and https://github.com/opennextjs/opennextjs-aws/pull/977#issuecomment-3261763114
      */
     if (keyLower === "location" && Array.isArray(value)) {
-      if (value[0] === value[1]) {
+      if (value.length === 1 || value[0] === value[1]) {
         result[keyLower] = value[0];
       } else {
         logger.warn(

packages/tests-unit/tests/http/utils.test.ts

@@ -65,4 +65,20 @@ describe("parseHeaders", () => {
       "x-opennext": "is-so-cool",
     });
   });
+
+  it("handles location header array with a single value", () => {
+    const headers = parseHeaders({
+      location: ["/target"],
+      "x-custom-header": "customValue",
+      "x-multiple-values": ["value1", "value2"],
+      "x-undefined-header": undefined,
+      "x-opennext": "is-so-cool",
+    } as unknown as http.OutgoingHttpHeaders);
+    expect(headers).toEqual({
+      location: "/target",
+      "x-custom-header": "customValue",
+      "x-multiple-values": "value1,value2",
+      "x-opennext": "is-so-cool",
+    });
+  });
 });