This playground showcases behavior of different Error handling operators available in Combine framework:
assertNoFailure
catch
mapError
setFailureType
retry
replaceError
SharedCode.swift
file (located in Sources) contains a definition of used Subject, errors and closures used in Playground's pages files.
Blog post about errors in Combine which describes examples from this playground
Should work well on Xcode 11.0 beta 4 (11M374r) and above.