vis-lua: only fail file_save_pre event if explicitly returned false

Previously we would also interpret a missing return value `nil` as
is the case when no pre save event handler is subscribed as failure.

1 files changed, 1 insertions, 1 deletions

diff --git a/vis-lua.c b/vis-lua.c
index 7318ec3..42196d1 100644
--- a/vis-lua.c
+++ b/vis-lua.c
@@ -2049,7 +2049,7 @@ bool vis_lua_file_save_pre(Vis *vis, File *file, const char *path) {
 		lua_pushstring(L, path);
 		if (pcall(vis, L, 2, 1) != 0)
 			return false;
-		return lua_toboolean(L, -1);
+		return !lua_isboolean(L, -1) || lua_toboolean(L, -1);
 	}
 	lua_pop(L, 1);
 	return true;