Internal error/crash: System.ArgumentException: not a measure abbreviation, or in correct kind

[KevinRansom]

[from auto-reported crashes]

Minimal repro:

type [<Measure>] N = foo // foo is undefined
type M2 = float<N>

This causes fsc to explode.

A number of internal errors are reported, then fsc crashes with Unhandled Exception: System.ArgumentException: not a measure abbreviation, or incorrect kind. Parameter name: tcref.

[investigation from Vlad]
Presumably error in reduceTyconRefAbbrevMeasureable is a cascading failure caused by some error upstream => it should be made more robust so exceptions won't be raised if abbreviation contains stub type created to handle errors.