Gracefully fail to resolve associated items instead of delay_span_bug.

compiler/rustc_middle/src/query/mod.rs

@@ -1145,7 +1145,7 @@ rustc_queries! {
 
     query codegen_fulfill_obligation(
         key: (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>)
-    ) -> Result<&'tcx ImplSource<'tcx, ()>, ErrorGuaranteed> {
+    ) -> Result<&'tcx ImplSource<'tcx, ()>, traits::CodegenObligationError> {
         cache_on_disk_if { true }
         desc { |tcx|
             "checking if `{}` fulfills its obligations",