GP-0: Fix tests

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/model/impl/GdbModelImpl.java

@@ -61,6 +61,7 @@ public class GdbModelImpl extends AbstractDebuggerObjectModel {
 
 	protected final GdbManager gdb;
 	protected final GdbModelTargetSession session;
+	private volatile boolean closed;
 
 	protected final CompletableFuture<GdbModelTargetSession> completedSession;
 	protected final GdbStateListener gdbExitListener = this::checkExited;
@@ -141,13 +142,22 @@ public class GdbModelImpl extends AbstractDebuggerObjectModel {
 	public CompletableFuture<Void> startGDB(String gdbCmd, String[] args) {
 		return CompletableFuture.runAsync(() -> {
 			try {
+				if (closed) {
+					return;
+				}
 				gdb.start(gdbCmd, args);
 			}
 			catch (IOException e) {
+				if (closed) {
+					return;
+				}
 				throw new DebuggerModelTerminatingException(
 					"Error while starting GDB: " + e.getMessage(), e);
 			}
 		}).thenCompose(__ -> {
+			if (closed) {
+				return AsyncUtils.NIL;
+			}
 			return gdb.runRC();
 		});
 	}
@@ -174,6 +184,7 @@ public class GdbModelImpl extends AbstractDebuggerObjectModel {
 
 	@Override
 	public CompletableFuture<Void> close() {
+		closed = true;
 		try {
 			terminate();
 			return super.close();

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/model/impl/GdbModelTargetSession.java

@@ -133,6 +133,9 @@ public class GdbModelTargetSession extends DefaultTargetModelRoot
 
 	@Override
 	public void output(GdbManager.Channel gdbChannel, String out) {
+		if (!valid) {
+			return;
+		}
 		TargetConsole.Channel dbgChannel;
 		switch (gdbChannel) {
 			case STDOUT: