THRIFT-2633 remove 'this is a dummy struct' structs from generated erlang

client: erlang
patch: talentdeficit (alisdair sullivan)

removes dummy struct info clauses from generated code and replaces
them with error that matches other undefined structs. adds error
for non-existent functions to function_info/2
diff --git a/lib/erl/src/thrift_client.erl b/lib/erl/src/thrift_client.erl
index c91c3ea..ff5c3dc 100644
--- a/lib/erl/src/thrift_client.erl
+++ b/lib/erl/src/thrift_client.erl
@@ -67,7 +67,9 @@
                                      seqid    = SeqId},
                    Function,
                    Args) ->
-    Params = Service:function_info(Function, params_type),
+    Params = try Service:function_info(Function, params_type)
+    catch error:function_clause -> no_function
+    end,
     case Params of
         no_function ->
             {Client, {error, {no_function, Function}}};