`Text/replace ""` triggers "Compiler bug"

[sjakobi]

At the current master:

$ cabal run -w ghc-8.10.4 dhall:dhall -- repl
Up to date
Welcome to the Dhall v1.38.1 REPL! Type :help for more information.
⊢ Text/replace ""

Error: Compiler bug                                                        
                                                                                
An ill-typed expression was encountered during normalization.                   
Explanation: This error message means that there is a bug in the Dhall compiler.
You didn't do anything wrong, but if you would like to see this problem fixed   
then you should report the bug at:                                              
                                                                                
https://github.com/dhall-lang/dhall-haskell/issues                              

CallStack (from HasCallStack):
  error, called at src/Dhall/Eval.hs:1201:13 in dhall-1.38.1-inplace:Dhall.Eval

This was found by the "everything well-typed should normalize" test in #2154 (comment).

[sjakobi]

This looks similar to the Natural/subtract 0 bug fixed in #1208.