From 6f480d3706c9f01f2f9044f4f016853a1e8239e6 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Fri, 8 Jan 2021 19:09:35 -0500
Subject: =?UTF-8?q?There's=20no=20identity=20element=20for=20=E2=88=BE?=
 =?UTF-8?q?=CB=9D=20on=20an=20empty=20list?=
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---
 src/r.bqn | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/r.bqn b/src/r.bqn
index cbbdfe7b..55c10950 100644
--- a/src/r.bqn
+++ b/src/r.bqn
@@ -399,7 +399,11 @@ _rankOp_←{
 _insert←{
   "˝: 𝕩 must have rank at least 1" ! 1≤=𝕩
   F←𝔽
-  Id ← {s←1 Drop ≢𝕩 ⋄ s joinPrim˙⊸≠◶⟨(0<↕∘≠)⊸×⊸⥊⟜⟨⟩, Reshape⟜Identity⟩ f}
+  Id ← {
+    s ← 1 Drop ≢𝕩
+    JoinSh ← {"˝: Identity does not exist"!0<≠𝕨 ⋄ 𝕨×0<↕≠𝕨}
+    s joinPrim˙⊸≠◶⟨JoinSh⥊𝕩˙, Reshape⟜Identity⟩ f
+  }
   𝕨 (0<≠)⊘1◶Id‿{𝕨F´<˘𝕩} 𝕩
 }
 ˝ ← _insert
-- 
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