add change file

Author: GarrettBeatty

.autover/changes/01370ae5-3537-4723-80b3-ee82e79e80b9.json

@@ -0,0 +1,11 @@
+{
+    "Projects": [
+      {
+        "Name": "AWS.Messaging",
+        "Type": "Patch",
+        "ChangelogMessages": [
+          "Update error message for handling scenario where subscriber mapping is not valid."
+        ]
+      }
+    ]
+  }