bugfix: Check for error type in productSelectorTypes (#23358)

Fixes #23156

Author: aherlihy

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -131,8 +131,11 @@ object Applications {
     else productSelectorTypes(tp, NoSourcePosition)
 
   def productSelectorTypes(tp: Type, errorPos: SrcPos)(using Context): List[Type] = {
-    val sels = for (n <- Iterator.from(0)) yield extractorMemberType(tp, nme.selectorName(n), errorPos)
-    sels.takeWhile(_.exists).toList
+    if tp.isError then
+      Nil
+    else
+      val sels = for (n <- Iterator.from(0)) yield extractorMemberType(tp, nme.selectorName(n), errorPos)
+      sels.takeWhile(_.exists).toList
   }
 
   def tupleComponentTypes(tp: Type)(using Context): List[Type] =

tests/neg/i23156.scala

@@ -0,0 +1,6 @@
+object Unpack {
+  (1, 2) match {
+    case Unpack(first, _) => first
+  }
+  def unapply(e: (Int, Int)): Option[T] = ??? // error
+}