Don't ice in validation when error body is created

compiler/rustc_const_eval/src/transform/validate.rs

@@ -60,6 +60,8 @@ impl<'tcx> MirPass<'tcx> for Validator {
                 ty::Closure(..) => Abi::RustCall,
                 ty::CoroutineClosure(..) => Abi::RustCall,
                 ty::Coroutine(..) => Abi::Rust,
+                // No need to do MIR validation on error bodies
+                ty::Error(_) => return,
                 _ => {
                     span_bug!(body.span, "unexpected body ty: {:?} phase {:?}", body_ty, mir_phase)
                 }

tests/ui/mir/validate/error-body.rs

@@ -0,0 +1,9 @@
+// compile-flags: -Zvalidate-mir
+
+fn _test() {
+    let x = || 45;
+    missing();
+    //~^ ERROR cannot find function `missing` in this scope
+}
+
+fn main() {}

tests/ui/mir/validate/error-body.stderr

@@ -0,0 +1,9 @@
+error[E0425]: cannot find function `missing` in this scope
+  --> $DIR/error-body.rs:5:5
+   |
+LL |     missing();
+   |     ^^^^^^^ not found in this scope
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0425`.