Error message for invalid IS method prints function body instead of method names

[ishaan-arora-1]

When passing an invalid importance sampling method directly to importance_sampling(), the error message is garbled because assert_importance_sampling_method_is_implemented() passes the function object implemented_is_methods to paste0() instead of calling implemented_is_methods().

Current output:

Error: Importance sampling method 'foo' is not implemented. Implemented methods: 'function () \nc("psis", "tis", "sis")'

Expected output:

Error: Importance sampling method 'foo' is not implemented. Implemented methods: 'psis', 'tis', 'sis'

The fix is a missing pair of parentheses on line 117 of R/importance_sampling.R.

[jgabry]

I think this was already fixed in your PR #326. Or is this different?

[ishaan-arora-1]

youre right, i was wondering the same thing. i could remember solving this, i wondered why it was still the same, just version differences, my bad.. thankyoou!!