Handle the possible case where the process launch failed
but we don't have an error message.

llvm-svn: 134662
diff --git a/lldb/tools/debugserver/source/debugserver.cpp b/lldb/tools/debugserver/source/debugserver.cpp
index 24e33e7..53f649d 100644
--- a/lldb/tools/debugserver/source/debugserver.cpp
+++ b/lldb/tools/debugserver/source/debugserver.cpp
@@ -228,12 +228,18 @@
 
     g_pid = pid;
 
-    if (pid == INVALID_NUB_PROCESS && strlen(launch_err_str) > 0)
+    if (pid == INVALID_NUB_PROCESS && strlen (launch_err_str) > 0)
     {
         DNBLogThreaded ("%s DNBProcessLaunch() returned error: '%s'", __FUNCTION__, launch_err_str);
         ctx.LaunchStatus().SetError(-1, DNBError::Generic);
         ctx.LaunchStatus().SetErrorString(launch_err_str);
     }
+    else if (pid == INVALID_NUB_PROCESS)
+    {
+        DNBLogThreaded ("%s DNBProcessLaunch() failed to launch process, unknown failure", __FUNCTION__);
+        ctx.LaunchStatus().SetError(-1, DNBError::Generic);
+        ctx.LaunchStatus().SetErrorString(launch_err_str);
+    }
     else
     {
         ctx.LaunchStatus().Clear();