Add APP_ERROR_NOT_READY to enum app_status

This can be used to indicate that some precondition is not met.

Bug: 168827302
Test: manual
Signed-off-by: Bill Richardson <wfrichar@google.com>
Change-Id: I16c3ce56e3803bc6d7550dd3cad3274a03940bc3
Reviewed-on: https://nugget-os-review.googlesource.com/c/host/generic/+/35744
Presubmit-Verified: TreeHugger Robot
Reviewed-by: Randall Spangler <rspangler@google.com>
diff --git a/nugget/include/application.h b/nugget/include/application.h
index ef70754..de771f0 100644
--- a/nugget/include/application.h
+++ b/nugget/include/application.h
@@ -314,6 +314,7 @@
   APP_ERROR_CHECKSUM,   /* checksum failed, only used within protocol */
   APP_ERROR_BUSY,       /* the app is already working on a commnad */
   APP_ERROR_TIMEOUT,    /* the app took too long to respond */
+  APP_ERROR_NOT_READY,  /* some required condition is not satisfied */
   /* more? */
 
   /*