patch 9.0.1317: crash when using an unset object variablev9.0.1317

Problem:    Crash when using an unset object variable.
Solution:   Give an error instead. (closes #12005)

4 files changed, 34 insertions, 7 deletions

diff --git a/src/errors.h b/src/errors.h
index 336c187d6..0bfafac1f 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -1182,6 +1182,8 @@ EXTERN char e_invalid_command[]
 	INIT(= N_("E476: Invalid command"));
 EXTERN char e_invalid_command_str[]
 	INIT(= N_("E476: Invalid command: %s"));
+EXTERN char e_invalid_command_str_expected_str[]
+	INIT(= N_("E476: Invalid command: %s, expected %s"));
 EXTERN char e_no_bang_allowed[]
 	INIT(= N_("E477: No ! allowed"));
 EXTERN char e_dont_panic[]
@@ -3442,6 +3444,6 @@ EXTERN char e_using_super_not_in_child_class[]
 	INIT(= N_("E1358: Using \"super\" not in a child class"));
 EXTERN char e_cannot_define_new_function_in_abstract_class[]
 	INIT(= N_("E1359: Cannot define a \"new\" function in an abstract class"));
-EXTERN char e_invalid_command_str_expected_str[]
-	INIT(= N_("E476: Invalid command: %s, expected %s"));
+EXTERN char e_using_null_object[]
+	INIT(= N_("E1360: Using a null object"));
 #endif
diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index be9b18e3a..f1aadde5d 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -182,6 +182,21 @@ def Test_class_interface_wrong_end()
   v9.CheckScriptFailure(lines, 'E476: Invalid command: endclass, expected endinterface')
 enddef
 
+def Test_object_not_set()
+  var lines =<< trim END
+      vim9script
+
+      class State
+        this.value = 'xyz'
+      endclass
+
+      var state: State 
+      var db = {'xyz': 789}
+      echo db[state.value]
+  END
+  v9.CheckScriptFailure(lines, 'E1360:')
+enddef
+
 def Test_class_member_initializer()
   var lines =<< trim END
       vim9script
diff --git a/src/version.c b/src/version.c
index 6cd2f1685..ff0b29ea1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1317,
+/**/
     1316,
 /**/
     1315,
diff --git a/src/vim9class.c b/src/vim9class.c
index ecf5de711..e11324d9c 100644
--- a/src/vim9class.c
+++ b/src/vim9class.c
@@ -1234,9 +1234,6 @@ class_object_index(
     evalarg_T	*evalarg,
     int		verbose UNUSED)	// give error messages
 {
-    // int		evaluate = evalarg != NULL
-    //				      && (evalarg->eval_flags & EVAL_EVALUATE);
-
     if (VIM_ISWHITE((*arg)[1]))
     {
 	semsg(_(e_no_white_space_allowed_after_str_str), ".", *arg);
@@ -1250,8 +1247,19 @@ class_object_index(
 	return FAIL;
     size_t len = name_end - name;
 
-    class_T *cl = rettv->v_type == VAR_CLASS ? rettv->vval.v_class
-					     : rettv->vval.v_object->obj_class;
+    class_T *cl;
+    if (rettv->v_type == VAR_CLASS)
+	cl = rettv->vval.v_class;
+    else // VAR_OBJECT
+    {
+	if (rettv->vval.v_object == NULL)
+	{
+	    emsg(_(e_using_null_object));
+	    return FAIL;
+	}
+	cl = rettv->vval.v_object->obj_class;
+    }
+
     if (*name_end == '(')
     {
 	int on_class = rettv->v_type == VAR_CLASS;