fix(ext/node): allow null value for req.setHeader (#21391)

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

2 files changed, 20 insertions, 1 deletions

diff --git a/cli/tests/unit_node/http_test.ts b/cli/tests/unit_node/http_test.ts
index b2b8eda0f..ae708c343 100644
--- a/cli/tests/unit_node/http_test.ts
+++ b/cli/tests/unit_node/http_test.ts
@@ -835,3 +835,22 @@ Deno.test("[node/https] node:https exports globalAgent", async () => {
     "node:https must export 'globalAgent' on module default export",
   );
 });
+
+Deno.test("[node/http] node:http request.setHeader(header, null) doesn't throw", () => {
+  {
+    const req = http.request("http://localhost:4545/");
+    req.on("error", () => {});
+    // @ts-expect-error - null is not a valid header value
+    req.setHeader("foo", null);
+    req.end();
+    req.destroy();
+  }
+  {
+    const req = https.request("https://localhost:4545/");
+    req.on("error", () => {});
+    // @ts-expect-error - null is not a valid header value
+    req.setHeader("foo", null);
+    req.end();
+    req.destroy();
+  }
+});
diff --git a/ext/node/polyfills/_http_outgoing.ts b/ext/node/polyfills/_http_outgoing.ts
index 8882ade55..1feb3e746 100644
--- a/ext/node/polyfills/_http_outgoing.ts
+++ b/ext/node/polyfills/_http_outgoing.ts
@@ -249,7 +249,7 @@ export class OutgoingMessage extends Stream {
     }
 
     name = name.toString();
-    headers[name.toLowerCase()] = [name, value.toString()];
+    headers[name.toLowerCase()] = [name, String(value)];
     return this;
   }