patch 8.2.1106: crash when trying to use s: variable in typed command

Problem:    Crash when trying to use s: variable in typed command.
Solution:   Don't use the script index when not set. (Ken Takata,
            closes #6366)

src/testdir/test_vimscript.vim

@@ -2007,6 +2007,7 @@ func Test_float_conversion_errors()
   endif
 endfunc
 
+" invalid function names               {{{1
 func Test_invalid_function_names()
   " function name not starting with capital
   let caught_e128 = 0
@@ -2067,7 +2068,7 @@ func Test_invalid_function_names()
   call delete('Xscript')
 endfunc
 
-" substring and variable name
+" substring and variable name              {{{1
 func Test_substring_var()
   let str = 'abcdef'
   let n = 3
@@ -2087,6 +2088,20 @@ func Test_substring_var()
   unlet b:nn
 endfunc
 
+" Test using s: with a typed command              {{{1
+func Test_typed_script_var()
+  CheckRunVimInTerminal
+
+  let buf = RunVimInTerminal('', {'rows': 6})
+
+  " Deep nesting of if ... endif
+  call term_sendkeys(buf, ":echo get(s:, 'foo', 'x')\n")
+  call TermWait(buf)
+  call WaitForAssert({-> assert_match('^E116:', term_getline(buf, 5))})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 "-------------------------------------------------------------------------------
 " Modelines								    {{{1
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1106,
 /**/
     1105,
 /**/

src/vim9compile.c

@@ -2339,6 +2339,9 @@ find_imported(char_u *name, size_t len, cctx_T *cctx)
     scriptitem_T    *si = SCRIPT_ITEM(current_sctx.sc_sid);
     int		    idx;
 
+    if (current_sctx.sc_sid <= 0)
+	return NULL;
+    si = SCRIPT_ITEM(current_sctx.sc_sid);
     if (cctx != NULL)
 	for (idx = 0; idx < cctx->ctx_imports.ga_len; ++idx)
 	{