Parse ASYNC used with 2 unimplemented functions cause UnhandledPromiseRejectionWarning

[KageAkuma75]

Hi Lester,

I have an issue with parseAsync :

If both arguments use not implemented function then we have an UnhandledPromiseRejectionWarning.

You can reproduce with this formula "SUM(NOTIMP1(2,1), NOTIMP2(3,4))"

I found a workaround by changing line 191 of /grammar/hooks.js from
'throw FormulaError.NOT_IMPLEMENTED(name);' to
'return FormulaError.NOT_IMPLEMENTED(name);' and it seems to work.

Best regards,

Jacques Loriot