Avoid uninitialized status in ALS job

for cases when Property_Error is raised and a job doesn't
handle it by it-self.

Refs eng/libadalang/libadalang#1490

Author: reznikmm

source/ada/lsp-ada_request_jobs.adb

@@ -38,6 +38,7 @@ package body LSP.Ada_Request_Jobs is
               (Client'Unchecked_Access);
          begin
             Self.Request.Visit_Server_Receiver (R);
+            Status := LSP.Server_Jobs.Done;
          end;
    end Execute_Request;