[GR-62734] Fix for transient issue where stack frames were null.

PullRequest: graal/20228

Author: javeleon

espresso/src/com.oracle.truffle.espresso.jdwp/src/com/oracle/truffle/espresso/jdwp/impl/DebuggerController.java

@@ -409,6 +409,7 @@ void stepOut(RequestFilter filter) {
     }
 
     private void doStepOut(SuspendedInfo susp) {
+        assert susp != null && !(susp instanceof UnknownSuspendedInfo);
         RootNode callerRoot = susp.getCallerRootNode();
         int stepOutBCI = context.getNextBCI(callerRoot, susp.getCallerFrame());
         SteppingInfo steppingInfo = commandRequestIds.get(susp.getThread());
@@ -1191,7 +1192,7 @@ private void continueStepping(SuspendedEvent event, SteppingInfo steppingInfo, O
                     break;
                 case STEP_OUT:
                     SuspendedInfo info = getSuspendedInfo(thread);
-                    if (info != null) {
+                    if (info != null && !(info instanceof UnknownSuspendedInfo)) {
                         doStepOut(info);
                     }
                     break;

espresso/src/com.oracle.truffle.espresso.jdwp/src/com/oracle/truffle/espresso/jdwp/impl/SuspendedInfo.java

@@ -72,7 +72,10 @@ public RootNode getCallerRootNode() {
     }
 
     public Frame getCallerFrame() {
-        return stackFrames.length > 1 ? stackFrames[1].getFrame() : null;
+        // use getStackFrames virtual call since this.stackFrames
+        // field can be null for unknown suspended info
+        CallFrame[] frames = getStackFrames();
+        return frames.length > 1 ? frames[1].getFrame() : null;
     }
 
     public void setForceEarlyReturnInProgress() {