chore: fix test breakage in error-reporting (googleapis#8966)

* chore: fix test breakage in error-reporting

* rollback to minimum set of changes required

* add test whitespace for readability

Author: pearigee

handwritten/error-reporting/src/request-extractors/hapi.ts

@@ -65,10 +65,11 @@ function extractRemoteAddressFromRequest(req: hapi.Request) {
 /**
  * Helper to normalize headers that might be arrays into a single string.
  */
-function getSingleHeader(
-  val: string | string[] | undefined,
-): string | undefined {
-  return Array.isArray(val) ? val[0] : val;
+function getSingleHeader(val: unknown): string | undefined {
+  if (Array.isArray(val)) {
+    return typeof val[0] === 'string' ? val[0] : undefined;
+  }
+  return typeof val === 'string' ? val : undefined;
 }
 
 /**

handwritten/error-reporting/test/unit/request-extractors/hapi.ts

@@ -138,5 +138,26 @@ describe('hapiRequestInformationExtractor behaviour', () => {
         EXPECTED,
       );
     });
+    it('Should handle array headers correctly', () => {
+      const REQUEST = {
+        ...FULL_REQ_DERIVATION_VALUE,
+        headers: {
+          'x-forwarded-for': ['0.0.0.1', '0.0.0.2'],
+          'user-agent': ['Mozilla/5.0', 'Chrome/90'],
+          referrer: ['www.ANOTHER-TEST.com'],
+        },
+      };
+      const EXPECTED = {
+        ...FULL_REQ_EXPECTED_VALUE,
+        userAgent: 'Mozilla/5.0',
+        referrer: 'www.ANOTHER-TEST.com',
+        remoteAddress: '0.0.0.1',
+      };
+      
+      deepStrictEqual(
+        hapiRequestInformationExtractor(REQUEST as {} as hapi.Request),
+        EXPECTED,
+      );
+    });
   });
 });