Serialization crashes do not result in known error codes

[devatwork]

Found by #349

!!! Crash found !!!
Selector: array:for-each(["theEcat", "sa*", "on the mat"], fn:tokenize#1)
Language: XPath3.1

Error: Serialization error: The value of an entry in an array is expected to be a single item or an empty sequence. Use nested arrays when putting multiple values in an array.
    at Object.multiple (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:652:182)
    at Object.next (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:62:278)
    at Object.next (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:58:985)
    at Xc.E.first (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:59:76)
    at Object.next (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:652:364)
    at Gu (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:656:268)
    at Object.Xx [as evaluateXPath] (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:658:116)
    at FuzzCase.run (C:\fontoxml\platform\fontoxpath\fuzzers\fuzzer.ts:73:3)
    at Engine.runWorker (C:\fontoxml\platform\fontoxpath\fuzzers\engine.ts:134:14)
    at Engine.run (C:\fontoxml\platform\fontoxpath\fuzzers\engine.ts:20:9)

!!! Crash found !!!
Selector: array:sort([(1,0), (1,1), (A,1), (0,0)])
Language: XQueryUpdate3.1

Error: Serialization error: The value of an entry in an array is expected to be a single item or an empty sequence. Use nested arrays when putting multiple values in an array.
    at Object.multiple (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:652:182)
    at Uc.E.ba (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:58:203)
    at Object.next (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:652:122)
    at Gu (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:656:268)
    at Object.Xx [as evaluateXPath] (C:\fontoxml\platform\fontoxpath\dist\fontoxpath.esm.js:658:116)
    at FuzzCase.run (C:\fontoxml\platform\fontoxpath\fuzzers\fuzzer.ts:73:3)
    at Engine.runWorker (C:\fontoxml\platform\fontoxpath\fuzzers\engine.ts:134:14)
    at Engine.run (C:\fontoxml\platform\fontoxpath\fuzzers\engine.ts:20:9)
    at Object.<anonymous> (C:\fontoxml\platform\fontoxpath\fuzzers\index.ts:48:9)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)