CompoundFilter.toJSON() throws when FunctionFilter present

[ghsolomon]

CompoundFilter.toJSON calls toJSON on its child filters:
https://github.com/xh/hoist-react/blob/c94ce756e930e6b32bf8d67271795b5db7b1892d/data/filter/CompoundFilter.ts#L70C1-L76C6

This will throw in the presence of a FunctionFilter since FunctionFilter does not have a toJSON method (functions are not serializable).

To fix, function filters should be omitted. Could consider flattening afterward as well.

[amcclain]

My concern about omitting is that you end up with an incomplete / inaccurate representation of the filter. I don't know that it would be a good idea to build that in - could result in bad surprises.

Although we could be throwing a more structured error, up front, in that method, if any function filters are nested within.

[ghsolomon]

Yeah a more structured error would work as well. Currently, invoking toJSON on a CompoundFilter containing FunctionFilters throws in a bit of a confusing way:

Example:
JSON.stringify(filterModel.filter) can throw this exception:

Uncaught: TypeError: f.toJSON is not a function
    at CompoundFilter.ts:51:53