ci: Fix weeder not stopping CI on error

Removes dead code that was unnoticed

Signed-off-by: Wolfgang Walther <walther@technowledgy.de>

nix/tools/tests.nix

@@ -133,7 +133,10 @@ let
         # build once before running all the tests
         ${cabal-install}/bin/cabal v2-build ${devCabalOptions} exe:postgrest lib:postgrest test:spec test:querycost
 
-        ${haskellPackages.weeder}/bin/weeder --config=./test/weeder.dhall || echo Found dead code: Check file list above.
+        (
+          trap 'echo Found dead code: Check file list above.' ERR ;
+          ${haskellPackages.weeder}/bin/weeder --config=./test/weeder.dhall
+        )
 
         # collect all tests
         HPCTIXFILE="$tmpdir"/io.tix \