fix(node/child_process): don't crash on undefined/null value of an env var (#20378)

Fixes #20373

---------

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

cli/tests/unit_node/child_process_test.ts

@@ -13,7 +13,7 @@ import {
 import { Deferred, deferred } from "../../../test_util/std/async/deferred.ts";
 import * as path from "../../../test_util/std/path/mod.ts";
 
-const { spawn, execFile, execFileSync, ChildProcess } = CP;
+const { spawn, spawnSync, execFile, execFileSync, ChildProcess } = CP;
 
 function withTimeout<T>(timeoutInMS = 10_000): Deferred<T> {
   const promise = deferred<T>();
@@ -640,3 +640,58 @@ Deno.test({
     assertEquals(cp.signalCode, "SIGIOT");
   },
 });
+
+// Regression test for https://github.com/denoland/deno/issues/20373
+Deno.test(async function undefinedValueInEnvVar() {
+  const promise = withTimeout<string>();
+  const env = spawn(
+    `"${Deno.execPath()}" eval -p "Deno.env.toObject().BAZ"`,
+    {
+      env: {
+        BAZ: "BAZ",
+        NO_COLOR: "true",
+        UNDEFINED_ENV: undefined,
+        // deno-lint-ignore no-explicit-any
+        NULL_ENV: null as any,
+      },
+      shell: true,
+    },
+  );
+  try {
+    let envOutput = "";
+
+    assert(env.stdout);
+    env.on("error", (err: Error) => promise.reject(err));
+    env.stdout.on("data", (data) => {
+      envOutput += data;
+    });
+    env.on("close", () => {
+      promise.resolve(envOutput.trim());
+    });
+    await promise;
+  } finally {
+    env.kill();
+  }
+  const value = await promise;
+  assertEquals(value, "BAZ");
+});
+
+// Regression test for https://github.com/denoland/deno/issues/20373
+Deno.test(function spawnSyncUndefinedValueInEnvVar() {
+  const ret = spawnSync(
+    `"${Deno.execPath()}" eval -p "Deno.env.toObject().BAZ"`,
+    {
+      env: {
+        BAZ: "BAZ",
+        NO_COLOR: "true",
+        UNDEFINED_ENV: undefined,
+        // deno-lint-ignore no-explicit-any
+        NULL_ENV: null as any,
+      },
+      shell: true,
+    },
+  );
+
+  assertEquals(ret.status, 0);
+  assertEquals(ret.stdout.toString("utf-8").trim(), "BAZ");
+});

ext/node/polyfills/internal/child_process.ts

@@ -53,6 +53,13 @@ export function mapValues<T, O>(
   const entries = Object.entries(record);
 
   for (const [key, value] of entries) {
+    if (typeof value === "undefined") {
+      continue;
+    }
+    if (value === null) {
+      continue;
+    }
+
     const mappedValue = transformer(value);
 
     ret[key] = mappedValue;
@@ -836,7 +843,7 @@ export function spawnSync(
     const output = new Deno.Command(command, {
       args,
       cwd,
-      env,
+      env: mapValues(env, (value) => value.toString()),
       stdout: toDenoStdio(normalizedStdio[1]),
       stderr: toDenoStdio(normalizedStdio[2]),
       uid,