Fix EPIPE error handling for process.stdout

When process.stdout encounters a broken pipe (EPIPE), it should emit an
error event so that applications can catch and handle it properly. This
fixes the Node.js compatibility test parallel/test-stdout-close-catch.js.

Changes:
- Modified PipeWriter.zig to propagate EPIPE errors when force_sync is
  enabled (indicating process stdio streams)
- For regular pipes, maintain existing behavior of treating EPIPE as
  completion to preserve compatibility
- Fixed error handling path in PipeWriter write function to properly
  return errors instead of ignoring them

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/io/PipeWriter.zig

@@ -37,11 +37,11 @@ pub fn PosixPipeWriter(
     return struct {
         fn tryWrite(this: *This, force_sync: bool, buf_: []const u8) WriteResult {
             return switch (if (!force_sync) getFileType(this) else .file) {
-                inline else => |ft| return tryWriteWithWriteFn(this, buf_, comptime writeToFileType(ft)),
+                inline else => |ft| return tryWriteWithWriteFn(this, buf_, force_sync, comptime writeToFileType(ft)),
             };
         }
 
-        fn tryWriteWithWriteFn(this: *This, buf: []const u8, comptime write_fn: *const fn (bun.FileDescriptor, []const u8) JSC.Maybe(usize)) WriteResult {
+        fn tryWriteWithWriteFn(this: *This, buf: []const u8, force_sync: bool, comptime write_fn: *const fn (bun.FileDescriptor, []const u8) JSC.Maybe(usize)) WriteResult {
             const fd = getFd(this);
 
             var offset: usize = 0;
@@ -54,6 +54,13 @@ pub fn PosixPipeWriter(
                         }
 
                         if (err.getErrno() == .PIPE) {
+                            // For process stdio (force_sync), emit EPIPE errors so they can be caught
+                            // For regular pipes, treat as completion to maintain compatibility
+                            if (force_sync) {
+                                log("EPIPE error in force_sync mode - propagating error", .{});
+                                return .{ .err = err };
+                            }
+                            log("EPIPE error in regular mode - converting to done", .{});
                             return .{ .done = offset };
                         }
 
@@ -651,7 +658,7 @@ pub fn PosixStreamingWriter(comptime Parent: type, comptime function_table: anyt
                     onWrite(this.parent, amt, .end_of_file);
                     return .{ .done = amt };
                 },
-                else => {},
+                else => |r| return r,
             }
 
             return rc;

test/js/node/test/parallel/test-stdout-close-catch.js

@@ -0,0 +1,27 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const child_process = require('child_process');
+const fixtures = require('../common/fixtures');
+const { getSystemErrorName } = require('util');
+
+const testScript = fixtures.path('catch-stdout-error.js');
+
+const child = child_process.exec(
+  ...common.escapePOSIXShell`"${process.execPath}" "${testScript}" | "${process.execPath}" -pe "process.stdin.on('data' , () => process.exit(1))"`
+);
+let output = '';
+
+child.stderr.on('data', function(c) {
+  output += c;
+});
+
+
+child.on('close', common.mustCall(function(code) {
+  output = JSON.parse(output);
+
+  assert.strictEqual(output.code, 'EPIPE');
+  assert.strictEqual(getSystemErrorName(output.errno), 'EPIPE');
+  assert.strictEqual(output.syscall, 'write');
+  console.log('ok');
+}));