From 1aaa38203650307a0dca98b954e36e04526728e8 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Mon, 7 Feb 2022 08:47:03 -0500
Subject: [PATCH] Avoid null index race-error during startup

---
 piker/ui/_cursor.py | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/piker/ui/_cursor.py b/piker/ui/_cursor.py
index d0f642e4..f6f8edde 100644
--- a/piker/ui/_cursor.py
+++ b/piker/ui/_cursor.py
@@ -109,11 +109,12 @@ class LineDot(pg.CurvePoint):
         # first = self._plot._arrays['ohlc'][0]['index']
         # first = x[0]
         # i = index - first
-        i = index - x[0]
-        if i > 0 and i < len(y):
-            newPos = (index, y[i])
-            QtWidgets.QGraphicsItem.setPos(self, *newPos)
-            return True
+        if index:
+            i = index - x[0]
+            if i > 0 and i < len(y):
+                newPos = (index, y[i])
+                QtWidgets.QGraphicsItem.setPos(self, *newPos)
+                return True
 
         return False