Show target VM exceptions as result in evaluate requests (#428)

This changes the result of an expression like `Long.parseLong("foo")`
sent to the evaluate handler from:

    org.eclipse.debug.core.DebugException: com.sun.jdi.InvocationException: Exception occurred in target VM occurred invoking method.

to the actual exception:

    NumberFormatException@76 "java.lang.NumberFormatException: For input string: "foo""
      backtrace: Object[6]@82
      cause: NumberFormatException@76
      depth: 46
      detailMessage: "For input string: "foo""
      stackTrace: StackTraceElement[0]@84
      suppressedExceptions: Collections$EmptyList@85 size=0

Author: mfussenegger

com.microsoft.java.debug.plugin/src/main/java/com/microsoft/java/debug/plugin/internal/eval/JdtEvaluationProvider.java

@@ -29,6 +29,7 @@
 import org.apache.commons.lang3.reflect.FieldUtils;
 import org.eclipse.core.resources.IWorkspaceRoot;
 import org.eclipse.core.resources.ResourcesPlugin;
+import org.eclipse.core.runtime.IStatus;
 import org.eclipse.debug.core.DebugException;
 import org.eclipse.debug.core.ILaunch;
 import org.eclipse.debug.core.ILaunchConfiguration;
@@ -328,9 +329,22 @@ private void internalEvaluate(ASTEvaluationEngine engine, ICompiledExpression co
         try  {
             engine.evaluateExpression(compiledExpression, stackframe, evaluateResult -> {
                 if (evaluateResult == null || evaluateResult.hasErrors()) {
-                    Exception ex = evaluateResult.getException() != null ? evaluateResult.getException()
-                            : new RuntimeException(StringUtils.join(evaluateResult.getErrorMessages()));
-                    completableFuture.completeExceptionally(ex);
+                    DebugException debugException = evaluateResult.getException();
+                    if (debugException == null) {
+                        completableFuture.completeExceptionally(
+                              new RuntimeException(String.join(" ", evaluateResult.getErrorMessages())));
+                        return;
+                    }
+                    IStatus status = debugException.getStatus();
+                    if (status.getCode() == DebugException.TARGET_REQUEST_FAILED) {
+                        Throwable innerException = status.getException();
+                        if (innerException instanceof com.sun.jdi.InvocationException) {
+                            ObjectReference objectReference = ((com.sun.jdi.InvocationException) innerException).exception();
+                            completableFuture.complete(objectReference);
+                            return;
+                        }
+                    }
+                    completableFuture.completeExceptionally(debugException);
                     return;
                 }
                 try {