Saving data into a nonexistent format kills Julia itself

[rdeits]

Related: https://discourse.julialang.org/t/using-fileio-meshio-to-save-a-homogenousmesh/4594

I can reproduce this in Julia v0.5 (where it causes Julia to hang and then produce an infinite stacktrace when killed) and in Julia v0.6 (where Julia segfaults immediately). Here's an example from Julia v0.6:

julia> using FileIO
INFO: Recompiling stale cache file /Users/rdeits/.julia/lib/v0.6/FileIO.ji for module FileIO.

julia> save(File{format"ASDFSDFSDFA"}("test.ply"), 1.0)
Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".Error encountered while saving "test.ply".
Fatal error:
Error encountered while saving "test.ply".
Fatal error:

signal (11): Segmentation fault: 11
while loading no file, in expression starting on line 0
unknown function (ip: 0xffffffffffffffff)
Allocations: 12406639 (Pool: 12397096; Big: 9543); GC: 31
[1]    59068 segmentation fault  julia

[rdeits]

Thanks!