Non-JSON serializable types throw an error when recorded with AppMap

[dustinbyrne]

Non-JSON serializable types can cause the application to panic.

FAILED tests/test.pt - TypeError: Object of type int64 is not JSON serializable
1 failed, 29 passed, 39 warnings in 10.53s

_appmap/generation.py:114: in default
    return json.JSONEncoder.default(self, o)

via https://appmap-group.slack.com/archives/C03GM7D2QRH/p1708366829827279

#312

[apotterri]

Rather than adding a special case for int64 to AppMapEncoder, we need to figure out a better way of handling unknown types.

Maybe something like

try:
    return json.JSONEncoder.default(self, o)
except TypeError:
    return repr(o) # or maybe str(o)

It would probably be good if the tests for this fix include some sort of simple app that uses numpy.