Auto merge of rust-lang#17348 - regexident:fix-type-or-const-param-so…

…urce, r=Veykril

Use `.get(…)` instead of `[…]` in `TypeOrConstParam::source(…)` and `LifetimeParam::source(…)`

Resolves rust-lang#17344.

crates/hir/src/has_source.rs

@@ -202,15 +202,15 @@ impl HasSource for TypeOrConstParam {
     type Ast = Either<ast::TypeOrConstParam, ast::TraitOrAlias>;
     fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
         let child_source = self.id.parent.child_source(db.upcast());
-        Some(child_source.map(|it| it[self.id.local_id].clone()))
+        child_source.map(|it| it.get(self.id.local_id).cloned()).transpose()
     }
 }
 
 impl HasSource for LifetimeParam {
     type Ast = ast::LifetimeParam;
     fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
         let child_source = self.id.parent.child_source(db.upcast());
-        Some(child_source.map(|it| it[self.id.local_id].clone()))
+        child_source.map(|it| it.get(self.id.local_id).cloned()).transpose()
     }
 }