Handle typeck errors properly

compiler/rustc_middle/src/query/mod.rs

@@ -220,7 +220,7 @@ rustc_queries! {
         desc { "checking if the crate is_panic_runtime" }
     }
 
-    /// Fetch the THIR for a given body.
+    /// Fetch the THIR for a given body. If typeck for that body failed, returns an empty `Thir`.
     query thir_body(key: ty::WithOptConstParam<LocalDefId>) -> (&'tcx Steal<thir::Thir<'tcx>>, thir::ExprId) {
         desc { |tcx| "building THIR for `{}`", tcx.def_path_str(key.did.to_def_id()) }
     }