SI-9135 Fix NPE, a regression in the pattern matcher

The community build discovered that #4252 introduced the possibility
for a NullPointerException. The tree with a null type was a synthetic
`Apply(<<matchEnd>>)` created by the pattern matcher.

This commit adds a null check.

1 files changed, 16 insertions, 0 deletions

diff --git a/test/files/pos/t9135.scala b/test/files/pos/t9135.scala
new file mode 100644
index 0000000000..1e2c97baf9
--- /dev/null
+++ b/test/files/pos/t9135.scala
@@ -0,0 +1,16 @@
+
+class Free[A] {
+  
+
+  this match {
+    case a @ Gosub() => gosub(a.a)(x => gosub(???)(???))
+  }
+  def gosub[A, B](a0: Free[A])(f0: A => Any): Free[B] = ???
+}
+
+  
+
+  case class Gosub[B]() extends Free[B] {
+    type C
+    def a: Free[C] = ???
+  }