MLBEDSW-3502: Add address checks

Added checks during command stream generation to make sure
that address boundaries are respected.

Change-Id: I4dbc693b42d54e35c8fcc785e8be88059e409eec
Signed-off-by: Louis Verhaard <louis.verhaard@arm.com>
diff --git a/ethosu/vela/errors.py b/ethosu/vela/errors.py
index 04468c9..918ca0a 100644
--- a/ethosu/vela/errors.py
+++ b/ethosu/vela/errors.py
@@ -22,6 +22,7 @@
 
     def __init__(self, data):
         self.data = f"Error! {data}"
+        self.error_msg = data
 
     def __str__(self):
         return repr(self.data)