Text3d: add assert's to check the selection and length are valid

source/blender/blenkernel/intern/font.c

@@ -463,6 +463,10 @@ int BKE_vfont_select_get(Object *ob, int *start, int *end)
 	
 	if (cu->editfont == NULL || ob->type != OB_FONT) return 0;
 
+	BLI_assert(cu->selstart >= 0 && cu->selstart <= cu->len + 1);
+	BLI_assert(cu->selend   >= 0 && cu->selend   <= cu->len + 1);
+	BLI_assert(cu->pos      >= 0 && cu->pos      <= cu->len);
+
 	if (cu->selstart == 0) return 0;
 	if (cu->selstart <= cu->selend) {
 		*start = cu->selstart - 1;

source/blender/editors/curve/editfont.c

@@ -237,6 +237,8 @@ static void update_string(Curve *cu)
 
 	/* Copy the wchar to UTF-8 */
 	BLI_strncpy_wchar_as_utf8(cu->str, ef->textbuf, len + 1);
+
+	BLI_assert(len == cu->len);
 }
 
 static int insert_into_textbuf(Object *obedit, uintptr_t c)