Invalid error message when functional index function returns scalar instead of array

[kshcherbatov]

e.g.

ufm_storage:create_index( 'PROF_HASH_1', {
            parts = { {1, 'string', is_nullable=true} },
            func = 'PROF_HASH_1_index_fun',
            if_not_exists = true, unique = false
        }
    )
func_body = [[ function(tup)
            local doc = tup[4]
            if (doc.attrs ~= nil) and (doc.attrs.strMap ~= nil)  then
                return doc.attrs.strMap.PROF_HASH_1
            end
            return nil
        end
    ]]

Error:

"type":"ClientError",
"message":"Key format doesn't mat ch one defined in functional index 'PROF_HASH_1' of space 'ufm_storage': supplied key type is invalid: expected boolean"

Fix:

                diag_set(ClientError, ER_FUNC_INDEX_FORMAT, it->index_def->name,
                         space ? space_name(space) : "",
                         tt_sprintf("supplied key type is invalid: expected %s",
-                                   field_type_strs[MP_ARRAY]));
+                                   field_type_strs[FIELD_TYPE_ARRAY]));