Fail on non-Object input for JSONObject instead of quietly returning empty Object - #90

Problem

JSONArrayDeserializer verifies that it was given a START_ARRAY (guard added for [datatype-json-org#15]), but JSONObjectDeserializer never got the equivalent check:

JSONObject ob = new JSONObject();
JsonToken t = p.currentToken();
if (t == JsonToken.START_OBJECT) {
    t = p.nextToken();
}
for (; t == JsonToken.PROPERTY_NAME; t = p.nextToken()) {

When the current token is not START_OBJECT, the loop simply does not run: an empty JSONObject is returned and the parser is left pointing in the middle of the value that was never consumed.

This silently produces wrong values rather than reporting an error:

The second case desyncs the parser outright; it only surfaces at all because FAIL_ON_TRAILING_TOKENS is enabled by default.

Fix

Add the matching guard, worded like the Array one, so both deserializers behave consistently:

Unexpected token (VALUE_NUMBER_INT), expected START_OBJECT for `org.json.JSONObject` value

Entry with a PROPERTY_NAME is still permitted, since a deserializer may be invoked with the parser already positioned inside the Object — TypeInformationTest continues to pass.

Tests

New FailOnNonObjectTest (7 cases): number/string/array input, the two list cases above that previously corrupted data, plus checks that {} and well-formed Object lists still work.

Full json-org suite: 19 tests, all green.