From 54f32d26937268c029221278cfd58ad7fd07e8d7 Mon Sep 17 00:00:00 2001
From: Li Haoyi <haoyi.sg@gmail.com>
Date: Sun, 9 Jul 2023 11:04:48 +0800
Subject: [PATCH] Improve `expected tagged dictionary` error message and make
 it work for non-empty dicts (#502)

Fixes https://github.com/com-lihaoyi/upickle/issues/500
---
 upickle/src/upickle/Api.scala               | 7 +++++--
 upickle/test/src/upickle/FailureTests.scala | 3 ++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/upickle/src/upickle/Api.scala b/upickle/src/upickle/Api.scala
index 4c461d6ce..5a39bb1a2 100644
--- a/upickle/src/upickle/Api.scala
+++ b/upickle/src/upickle/Api.scala
@@ -274,11 +274,14 @@ trait AttributeTagged extends Api with Annotator{
         }
       }
       def visitEnd(index: Int) = {
-        if (context == null) throw new Abort("expected tagged dictionary")
+        def missingKeyMsg = s"""Missing key "$tagName" for tagged dictionary"""
+        if (context == null) throw new Abort(missingKeyMsg)
         else if (fastPath) context.visitEnd(index).asInstanceOf[T]
         else{
           val x = context.visitEnd(index).asInstanceOf[IndexedValue.Obj]
-          val keyAttr = x.value0.find(_._1.toString == tagName).get._2
+          val keyAttr = x.value0.find(_._1.toString == tagName)
+            .getOrElse(throw new Abort(missingKeyMsg))
+            ._2
           val key = keyAttr.asInstanceOf[IndexedValue.Str].value0.toString
           val delegate = taggedReader.findReader(key)
           if (delegate == null){
diff --git a/upickle/test/src/upickle/FailureTests.scala b/upickle/test/src/upickle/FailureTests.scala
index 4ccd5bc84..2f915891f 100644
--- a/upickle/test/src/upickle/FailureTests.scala
+++ b/upickle/test/src/upickle/FailureTests.scala
@@ -227,7 +227,8 @@ object FailureTests extends TestSuite {
           test - assertErrorMsgDefault[Fi.Fo]("""{"$type": "omg"}""", "invalid tag for tagged object: omg at index 1")
           test - assertErrorMsgDefault[Fi](""""omg"""", "invalid tag for tagged object: omg at index 0")
           test - assertErrorMsgDefault[Fi]("""{"$type": "omg"}""", "invalid tag for tagged object: omg at index 1")
-          test - assertErrorMsgDefault[Fi]("""{}""", "expected tagged dictionary")
+          test - assertErrorMsgDefault[Fi]("""{}""", """Missing key "$type" for tagged dictionary at index 1""")
+          test - assertErrorMsgDefault[Fi]("""{"mispelledTypeTag": "omg"}""", """Missing key "$type" for tagged dictionary at index 26""")
         }
 
         test("taggedInvalidBody"){