fix: add type hints for nullable columns

src/entities/Link.ts

@@ -8,7 +8,7 @@ export class Link {
 	id: number
 
 	@Column({ nullable: true })
-	subdomain: string
+	subdomain: string | null
 
 	@Column()
 	shortUri: string
@@ -25,7 +25,7 @@ export class Link {
 	@Column('bigint')
 	expiryDate: number
 
-	@ManyToOne(() => User, (user) => user.links)
+	@ManyToOne(() => User, (user) => user.links, { nullable: true })
 	@JoinTable()
-	author: User
+	author: User | null
 }