Memory leak during build with ncc - conditional properties

We are using ncc for a big project amd while migrating to typescript error with memory leak occured during project building with ncc.
That might be related to settings (maybe?) of ncc, but while returning conditional properties - memory leak is popping up.
Example:
Let's say we return object with many conditional properties:

... 
return {
    ...(conditionalProp1 && {conditionalProp1}),
    ... //etc.
}

Then during building it crashes at actually nothing helps. Have anyone had similar issue?
The "walkaround" solution for it is to create a function which omits all of the empty/falsy properties and then it works normally.

Start by reproducing an ncc build using the conditional object properties shown in the issue, then compare it with the workaround that removes falsy properties. A complete fix would prevent the build from exhausting memory or crashing for this pattern, but the issue provides no named files or tests.