diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
index a83628c65cf4..9273bef4b9f5 100644
--- a/compiler/src/dotty/tools/dotc/core/Types.scala
+++ b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -542,16 +542,17 @@ object Types {
      *  Inherited by all type proxies. Overridden for And and Or types.
      *  `Nil` for all other types.
      */
-    def baseClasses(using Context): List[ClassSymbol] = {
+    def baseClasses(using Context): List[ClassSymbol] =
       record("baseClasses")
-      this match {
-        case tp: TypeProxy =>
-          tp.underlying.baseClasses
-        case tp: ClassInfo =>
-          tp.cls.classDenot.baseClasses
-        case _ => Nil
-      }
-    }
+      try
+        this match
+          case tp: TypeProxy =>
+            tp.underlying.baseClasses
+          case tp: ClassInfo =>
+            tp.cls.classDenot.baseClasses
+          case _ => Nil
+      catch case ex: Throwable =>
+        handleRecursive("base classes of", this.show, ex)
 
 // ----- Member access -------------------------------------------------
 
diff --git a/compiler/src/dotty/tools/dotc/typer/Namer.scala b/compiler/src/dotty/tools/dotc/typer/Namer.scala
index 0969fe29009e..ef1f0d225d1a 100644
--- a/compiler/src/dotty/tools/dotc/typer/Namer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Namer.scala
@@ -1345,8 +1345,11 @@ class Namer { typer: Typer =>
           // TODO: Look only at member of supertype instead?
           lazy val schema = paramFn(WildcardType)
           val site = sym.owner.thisType
-
-          sym.owner.info.baseClasses.tail.foldLeft(NoType: Type) { (tp, cls) =>
+          val bcs = sym.owner.info.baseClasses
+          if bcs.isEmpty then
+            assert(ctx.reporter.errorsReported)
+            NoType
+          else bcs.tail.foldLeft(NoType: Type) { (tp, cls) =>
             def instantiatedResType(info: Type, paramss: List[List[Symbol]]): Type = info match
               case info: PolyType =>
                 paramss match
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 91ebd333c051..7ab102186a5e 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -1320,7 +1320,9 @@ class Typer extends Namer
                   EmptyTree
             }
           case tp =>
-            throw new java.lang.Error(i"internal error: closing over non-method $tp, pos = ${tree.span}")
+            if !tp.isErroneous then
+              throw new java.lang.Error(i"internal error: closing over non-method $tp, pos = ${tree.span}")
+            TypeTree(defn.AnyType)
         }
       else typed(tree.tpt)
     //println(i"typing closure $tree : ${meth1.tpe.widen}")
diff --git a/tests/neg/i9299.scala b/tests/neg/i9299.scala
new file mode 100644
index 000000000000..6c23d11553ff
--- /dev/null
+++ b/tests/neg/i9299.scala
@@ -0,0 +1,4 @@
+type F <: F = 1 match { // error
+  case _ => foo.foo // error // error
+}
+def foo(a: Int): Unit = ???
diff --git a/tests/neg/i9299a.scala b/tests/neg/i9299a.scala
new file mode 100644
index 000000000000..bc3ec57b947b
--- /dev/null
+++ b/tests/neg/i9299a.scala
@@ -0,0 +1,4 @@
+type T <: foo.a = Int match { // error
+  case "" => foo.b // error
+}
+def foo(x: Int): Unit = ???
\ No newline at end of file