Fix ICE in redundant_pattern_matching

clippy_utils/src/ty.rs

@@ -257,10 +257,12 @@ pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symb
     }
 }
 
-/// Checks if the type is equal to a lang item
+/// Checks if the type is equal to a lang item.
+///
+/// Returns `false` if the `LangItem` is not defined.
 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
     match ty.kind() {
-        ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
+        ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).map_or(false, |li| li == adt.did),
         _ => false,
     }
 }