use nullish coalescing

Author: a-tarasyuk

src/compiler/checker.ts

@@ -9595,9 +9595,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                         jsdocType = getAnnotatedTypeForAssignmentDeclaration(jsdocType, expression, symbol, declaration);
                     }
                     if (!jsdocType) {
-                        (types || (types = [])).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType);
+                        (types ??= []).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType);
                     }
-                    (declarations || (declarations = [])).push(declaration);
+                    (declarations ??= []).push(declaration);
                 }
                 type = jsdocType;
             }