From 16dfc75ad08e8af4c620945d63ce31861bff21d4 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Thu, 13 Jan 2022 16:05:05 -0500
Subject: [PATCH] Add guard for "last step" rect

---
 piker/ui/_curve.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/piker/ui/_curve.py b/piker/ui/_curve.py
index 161332d5..15b19f76 100644
--- a/piker/ui/_curve.py
+++ b/piker/ui/_curve.py
@@ -328,8 +328,10 @@ class FastAppendCurve(pg.PlotCurveItem):
         profiler = pg.debug.Profiler(disabled=not pg_profile_enabled())
         # p.setRenderHint(p.Antialiasing, True)
 
-        if self._step_mode:
-
+        if (
+            self._step_mode
+            and self._last_step_rect
+        ):
             brush = self.opts['brush']
             # p.drawLines(*tuple(filter(bool, self._last_step_lines)))
             # p.drawRect(self._last_step_rect)