remove hardcoded "ERROR: TODO: ..." output from TypedValueFormatter

- otherwise this gets outputted in the client when using {{#property}} with a time data value

Change-Id: Ib8f775b092bc1a02a97784d721bef97eda9676dd
(bug 48938) handle exception for unknown data type when formatting PropertyValueSnak

Change-Id: I6727f376566b7ef2c1b3e96de6e4517b008e887a