Visit the page /api/transaction.search and set objectType="XACT" and Call Method.
You do not see anymore this confusing exception:
get_class() expects parameter 1 to be object, null given
Instead, you see this informative exception message:
In call to "transaction.search", specified "objectType" ("XACT") is not supported because it does not implement "newObject()". Valid object types are: ABND, ADEV, AINT, ANAM, ANET, ASRV, DIFF, DREV, BOOK, DRYB, FBAK, FITV, HMBD, HMCP, HMCS, HMBB, HRUL, HWBH, HWBR, TASK, NUAI, NUAQ, NUAS, CDTL, FPRV, AUTH, CTNM, AMSG, APAS, AKEY, BDGE, CEVT, CEXP, CIMP, CONF, CONP, CDWN, DSHB, DSHP, PRTL, FORM, FILE, LEGD, MCRO, APPE, OASC, OPKG, PPAK, PPUB, PVER, PSTE, USER, BLOG, POST, PHRL, PANL, PCOL, PROJ, WTRG, CMIT, RIDT, REPO, RURI, POLL, SPCE, PSET, BULK, PVAR, MOCK, AEML, ACNT, CART, PMRC, PAYM, PHPR, PSUB, WIKI, ANSW, QUES.
Moreover, visit the homepage of the Conduit API /api/transaction.search and enjoy the new amazing table.