patch 8.2.0031: MS-Windows: test for empty job fails

Problem:    MS-Windows: test for empty job fails
Solution:   Check for error message, make it also fail on Unix.
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index 24a7ae4..a7c4009 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -1960,8 +1960,8 @@
 
 func Test_empty_job()
   " This was crashing on MS-Windows.
-  let job = job_start([""])
-  call WaitForAssert({-> assert_equal("dead", job_status(job))})
+  call assert_fails('let job = job_start([""])', 'E474:')
+  call assert_fails('let job = job_start(["   "])', 'E474:')
 endfunc
 
 " Do this last, it stops any channel log.