Don't lookup method handle writes if we don't have access info

The other usages of access info is already doing null checks

Bug: 252930366
Change-Id: I373caa7c4bf3f7b514ece01e02aaa9c6d2727c36

src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java

diff --git a/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java b/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java
index d05ea55..0db5825 100644
--- a/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java
+++ b/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java
@@ -131,7 +131,8 @@
           field -> {
             FieldAccessInfo accessInfo = fieldAccessInfos.get(field.getReference());
             KeepFieldInfo keepInfo = appView.getKeepInfo(field);
-            if (keepInfo.isPinned(appView.options()) || accessInfo.isWrittenFromMethodHandle()) {
+            if (keepInfo.isPinned(appView.options())
+                || (accessInfo != null && accessInfo.isWrittenFromMethodHandle())) {
               fieldStates.put(field.getDefinition(), FieldState.unknown());
             }
           });