From 9f94ad265cab3c6a05c6aff32c71af4873583ff2 Mon Sep 17 00:00:00 2001
From: Scott Cain <scott+git@scottcain.net>
Date: Mon, 25 Nov 2024 10:00:08 -0800
Subject: [PATCH] fixing the start coord to avoid negative numbers

---
 lib/src/accessFasta.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/src/accessFasta.ts b/lib/src/accessFasta.ts
index 1fe5b27..87a473f 100644
--- a/lib/src/accessFasta.ts
+++ b/lib/src/accessFasta.ts
@@ -17,7 +17,7 @@ export async function accessFasta(
     gzi: gziFilehandle,
   });
 
-  const upstreamstart = start - 499;
+  const upstreamstart = start - 499 < 0 ? 0 : start - 499;
   const downstreamend = end + 499;
   const seq = await t.getSequence(refseq, start, end);
   const upstream = await t.getSequence(refseq, upstreamstart, start);