patch 8.1.2357: no test with wrong argument for rand()

Problem:    No test with wrong argument for rand().
Solution:   Add a test case.
diff --git a/src/testdir/test_random.vim b/src/testdir/test_random.vim
index f8ea407..747e438 100644
--- a/src/testdir/test_random.vim
+++ b/src/testdir/test_random.vim
@@ -25,7 +25,11 @@
   let v = rand()
   call assert_notequal(v, rand())
 
+  if has('float')
+    call assert_fails('echo srand(1.2)', 'E805:')
+  endif
   call assert_fails('echo srand([1])', 'E745:')
+  call assert_fails('echo rand("burp")', 'E475:')
   call assert_fails('echo rand([1, 2, 3])', 'E475:')
   call assert_fails('echo rand([[1], 2, 3, 4])', 'E475:')
   call assert_fails('echo rand([1, [2], 3, 4])', 'E475:')
diff --git a/src/version.c b/src/version.c
index 7abb190..d063809 100644
--- a/src/version.c
+++ b/src/version.c
@@ -738,6 +738,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2357,
+/**/
     2356,
 /**/
     2355,