From 5c3ef810d1e8e3fdde3cfc115a850748a95dbbdf Mon Sep 17 00:00:00 2001
From: odersky <odersky@gmail.com>
Date: Tue, 14 Jun 2022 14:29:14 +0200
Subject: [PATCH] Recover from TypeErrors in isErroneous

Fixes #15283 (hopefully)
---
 compiler/src/dotty/tools/dotc/core/Types.scala | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
index 6a5d48866158..838754d13299 100644
--- a/compiler/src/dotty/tools/dotc/core/Types.scala
+++ b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -353,7 +353,8 @@ object Types {
      *
      */
     def isErroneous(using Context): Boolean =
-      widen.existsPart(_.isError, forceLazy = false)
+      try widen.existsPart(_.isError, forceLazy = false)
+      catch case ex: TypeError => true
 
     /** Is this type unusable for implicit search or overloading resolution
      *  since it has embedded errors that can match anything? This is weaker and more