patch 8.2.2184: Vim9: no error when using "2" for a line number

Problem:    Vim9: no error when using "2" for a line number.
Solution:   Give an error message if the line number is invalid. (closes #7492)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index d40f89f..cf9c2c4 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -2615,6 +2615,8 @@
     else
     {
 	line = tv_get_lnum(argvars);
+	if (line < 0)
+	    semsg(_(e_invarg2), tv_get_string(&argvars[0]));
 	col = (long)tv_get_number_chk(&argvars[1], NULL);
 	if (argvars[2].v_type != VAR_UNKNOWN)
 	    coladd = (long)tv_get_number_chk(&argvars[2], NULL);
diff --git a/src/testdir/test_cursor_func.vim b/src/testdir/test_cursor_func.vim
index d914067..cbaad24 100644
--- a/src/testdir/test_cursor_func.vim
+++ b/src/testdir/test_cursor_func.vim
@@ -30,7 +30,7 @@
   call cursor(1, 1, 1)
   call assert_equal([1, 1, 1], getcurpos()[1:3])
 
-  call assert_equal(-1, cursor(-1, -1))
+  call assert_fails('call cursor(-1, -1)', 'E475:')
 
   quit!
 endfunc
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index a050467..0f03d1f 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -185,6 +185,20 @@
   count('ABC ABC ABC', 'b', false)->assert_equal(0)
 enddef
 
+def Test_cursor()
+  new
+  setline(1, range(4))
+  cursor(2, 1)
+  assert_equal(2, getcurpos()[1])
+  cursor('$', 1)
+  assert_equal(4, getcurpos()[1])
+
+  var lines =<< trim END
+    cursor('2', 1)
+  END
+  CheckDefExecAndScriptFailure(lines, 'E475:')
+enddef
+
 def Test_executable()
   assert_false(executable(""))
   assert_false(executable(test_null_string()))
diff --git a/src/typval.c b/src/typval.c
index affd668..df3bc92 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -1536,11 +1536,11 @@
     linenr_T
 tv_get_lnum(typval_T *argvars)
 {
-    linenr_T	lnum = 0;
+    linenr_T	lnum = -1;
 
     if (argvars[0].v_type != VAR_STRING || !in_vim9script())
 	lnum = (linenr_T)tv_get_number_chk(&argvars[0], NULL);
-    if (lnum == 0)  // no valid number, try using arg like line()
+    if (lnum <= 0)  // no valid number, try using arg like line()
     {
 	int	fnum;
 	pos_T	*fp = var2fpos(&argvars[0], TRUE, &fnum);
diff --git a/src/version.c b/src/version.c
index bebfa11..0575763 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2184,
+/**/
     2183,
 /**/
     2182,