The issue is caused by compiling druntime/phobos and the application
with different flags. The template instance for __switch_errorT is not
included in the build of druntime/phobos, because they are compiled
with -release. DMD will also not include it in an application compiled
without -release, because it assumes, that it is already in druntime.
See comment https://issues.dlang.org/show_bug.cgi?id=20802#c3 by Spoov.
The template instance for __switch_errorT is now always instantiated in
druntime, so it is part of the ABI of druntime.
