patch 8.2.1751: using 2 where bool is expected may throw an error

Problem:    Using 2 where bool is expected may throw an error.
Solution:   Make this backwards compatible.
diff --git a/src/evalfunc.c b/src/evalfunc.c
index afc8977..b387c8c 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1982,7 +1982,7 @@
     if (argvars[1].v_type != VAR_UNKNOWN)
 	noref = (int)tv_get_bool_chk(&argvars[1], NULL);
     if (noref < 0 || noref > 1)
-	emsg(_(e_invarg));
+	semsg(_(e_using_number_as_bool_nr), noref);
     else
     {
 	copyID = get_copyID();
@@ -8193,7 +8193,7 @@
     if (argvars[1].v_type != VAR_UNKNOWN)
 	skipcc = (int)tv_get_bool(&argvars[1]);
     if (skipcc < 0 || skipcc > 1)
-	emsg(_(e_invarg));
+	semsg(_(e_using_number_as_bool_nr), skipcc);
     else
     {
 	func_mb_ptr2char_adv = skipcc ? mb_ptr2char_adv : mb_cptr2char_adv;
diff --git a/src/testdir/test_search.vim b/src/testdir/test_search.vim
index ca06c34..e39458f 100644
--- a/src/testdir/test_search.vim
+++ b/src/testdir/test_search.vim
@@ -290,6 +290,9 @@
   new
   call setline(1, ['other code', 'here [', ' [', ' " cursor here', ' ]]'])
 
+  " should not give an error for using "42"
+  call assert_equal(0, searchpair('a', 'b', 'c', '', 42))
+
   4
   call assert_equal(3, searchpair('\[', '', ']', 'bW'))
   call assert_equal([0, 3, 2, 0], getpos('.'))
diff --git a/src/testdir/test_terminal2.vim b/src/testdir/test_terminal2.vim
index 87d1e35..64310f6 100644
--- a/src/testdir/test_terminal2.vim
+++ b/src/testdir/test_terminal2.vim
@@ -560,8 +560,8 @@
     endif
   endif
 
-  call assert_fails('call term_gettty(buf, 2)', 'E1023:')
-  call assert_fails('call term_gettty(buf, -1)', 'E1023:')
+  call assert_fails('call term_gettty(buf, 2)', 'E475:')
+  call assert_fails('call term_gettty(buf, -1)', 'E475:')
 
   call assert_equal('', term_gettty(buf + 1))
 
diff --git a/src/typval.c b/src/typval.c
index 1db0d77..5151f72 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -177,7 +177,7 @@
     switch (varp->v_type)
     {
 	case VAR_NUMBER:
-	    if (want_bool && varp->vval.v_number != 0
+	    if (in_vim9script() && want_bool && varp->vval.v_number != 0
 						   && varp->vval.v_number != 1)
 	    {
 		semsg(_(e_using_number_as_bool_nr), varp->vval.v_number);
diff --git a/src/version.c b/src/version.c
index a8b907d..90ec322 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1751,
+/**/
     1750,
 /**/
     1749,