[REG2.064] Issue 13221 - [ICE] '0' on line 318 in file 'interpret.c'

https://issues.dlang.org/show_bug.cgi?id=13221
Does this change imply expressions may reach `ctfeInterpret` with an error type that somehow have not been replaced with error expressions?  Is this legitimate or should the type check be replaced with an assert?