Fixed an issue with broken await using declarations in for of loops (#56466)

Co-authored-by: Jake Bailey <5341706+jakebailey@users.noreply.github.com>

src/compiler/checker.ts

@@ -50935,7 +50935,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                         return true;
                     }
                 }
-                return false;
             }
         }
 

src/compiler/transformers/esnext.ts

@@ -14,6 +14,7 @@ import {
     ExportAssignment,
     ExportSpecifier,
     Expression,
+    firstOrUndefined,
     ForOfStatement,
     ForStatement,
     GeneratedIdentifierFlags,
@@ -305,11 +306,7 @@ export function transformESNext(context: TransformationContext): (x: SourceFile
             //
             // before handing the shallow transformation back to the visitor for an in-depth transformation.
             const forInitializer = node.initializer;
-            Debug.assertNode(forInitializer, isUsingVariableDeclarationList);
-            Debug.assert(forInitializer.declarations.length === 1, "ForInitializer may only have one declaration");
-
-            const forDecl = forInitializer.declarations[0];
-            Debug.assert(!forDecl.initializer, "ForInitializer may not have an initializer");
+            const forDecl = firstOrUndefined(forInitializer.declarations) || factory.createVariableDeclaration(factory.createTempVariable(/*recordTempVariable*/ undefined));
 
             const isAwaitUsing = getUsingKindOfVariableDeclarationList(forInitializer) === UsingKind.Async;
             const temp = factory.getGeneratedNameForNode(forDecl.name);