Issue type:

[x] bug report

Database system/driver:

[x] postgres

TypeORM version:

[x] latest

Steps to reproduce or a small repository showing the problem:

// ./Doc.entity.ts
@Entity()
export class Doc {
	@PrimaryGeneratedColumn("uuid")
	id: string;

	@Column("varchar", {
		length: 2000,
		nullable: true,
		// marshall 
		transformer: {
			from(value: string | null): URL | null {
				return value !== null ? new URL(value) : value;
			},
			to(value: URL | null): string | null {
				return value?.toString() || null;
			},
		},
	})
	url: URL | null;
}

// elsewhere…

const doc = new Doc();
doc.url = new URL("https://typeorm.io/")

await repository.save(doc); // <- throws here with `TypeError: Cannot set property 'flags' of undefined`

The stack trace suggests that Node internals for URL are throwing here
https://github.com/nodejs/node/blob/2fa74e3e38bb028339e48763138456b3ed10ed97/lib/internal/url.js#L240 (ctx is undefined?)
after href#set is called: https://github.com/nodejs/node/blob/2fa74e3e38bb028339e48763138456b3ed10ed97/lib/internal/url.js#L458

which is triggered from the TypeORM library here:

I've previously employed richer types + transformers for other data types flawlessly. However, this data type (URL) fails before it even gets to the transformers to Marshall to the database.

I'm not familiar enough with the inner workings of how TypeORM serializes its data to break this problem down. Is there something about the URL data type specifically that prevents it from working as expected?

In the meantime, I can work with the data type as a string, and transform it to a URL manually.