Malformed array literal when handling single backslash in an array

[Strengthless]

Describe the bug
When calling em.upsert('Book', { SCODE: 'AGSj', title: ['\\'] }), the command fails.

Stack trace

 ⨯ DriverException: insert into "book" ("scode", "title") values ('AGSj',  E'{\\}') on conflict ("scode") do update set "title" = excluded."title" returning "author", "call_number", "discipline", "isbn", "type", "image" - malformed array literal: "{\}"
    at PostgreSqlExceptionConverter.convertException ([redacted]/node_modules/@mikro-orm/core/platforms/ExceptionConverter.js:8:16)
    at PostgreSqlExceptionConverter.convertException ([redacted]/node_modules/@mikro-orm/postgresql/PostgreSqlExceptionConverter.js:42:22)
    at PostgreSqlDriver.convertException (/[redacted]/node_modules/@mikro-orm/core/drivers/DatabaseDriver.js:201:54)
    at [redacted]/node_modules/@mikro-orm/core/drivers/DatabaseDriver.js:205:24
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async PostgreSqlDriver.nativeUpdate ([redacted]/node_modules/@mikro-orm/knex/AbstractSqlDriver.js:379:19)
    at async SqlEntityManager.upsert ([redacted]/node_modules/@mikro-orm/core/EntityManager.js:496:21)
    at async GET (webpack-internal:///(rsc)/./src/app/api/test/route.ts:16:5)
    at async [redacted]/node_modules/next/dist/compiled/next-server/app-route.runtime.dev.js:6:62361

previous error: insert into "book" ("scode", "title") values ('AGSj',  E'{\\}') on conflict ("scode") do update set "title" = excluded."title" returning "author", "call_number", "discipline", "isbn", "type", "image" - malformed array literal: "{\}"
    at Parser.parseErrorMessage ([redacted]/node_modules/pg-protocol/dist/parser.js:287:98)
    at Parser.handlePacket ([redacted]/node_modules/pg-protocol/dist/parser.js:126:29)
    at Parser.parse ([redacted]/node_modules/pg-protocol/dist/parser.js:39:38)
    at Socket.<anonymous> ([redacted]/node_modules/pg-protocol/dist/index.js:11:42)
    at Socket.emit (node:events:514:28)
    at addChunk (node:internal/streams/readable:343:12)
    at readableAddChunk (node:internal/streams/readable:316:9)
    at Readable.push (node:internal/streams/readable:253:10)
    at TCP.onStreamRead (node:internal/stream_base_commons:190:23)
    at TCP.callbackTrampoline (node:internal/async_hooks:130:17) {
  length: 119,
  severity: 'ERROR',
  code: '22P02',
  detail: 'Unexpected end of input.',
  hint: undefined,
  position: '56',
  internalPosition: undefined,
  internalQuery: undefined,
  where: undefined,
  schema: undefined,
  table: undefined,
  column: undefined,
  dataType: undefined,
  constraint: undefined,
  file: 'arrayfuncs.c',
  line: '491',
  routine: 'ArrayCount'
}

To Reproduce
Steps to reproduce the behavior:

1. Upsert data including an array with only a single backslash, e.g.:

em.upsert('Book', { SCODE: 'AGSj', title: ['\\'] })

2. Observe the error.

Expected behavior
The upsert should perform without errors.

Additional context

1. This is likely a PostgreSQL driver-specific issue, with the parser translating JS arrays into Postgres arrays failing.
2. Related issue: type: string[] - malformed array literal when setting a value that includes the character "," #3810
3. Working patch, can make a PR if this looks good:

diff --git a/node_modules/@mikro-orm/postgresql/PostgreSqlPlatform.js b/node_modules/@mikro-orm/postgresql/PostgreSqlPlatform.js
index 499637a..f8db08d 100644
--- a/node_modules/@mikro-orm/postgresql/PostgreSqlPlatform.js
+++ b/node_modules/@mikro-orm/postgresql/PostgreSqlPlatform.js
@@ -113,7 +113,7 @@ class PostgreSqlPlatform extends knex_1.AbstractSqlPlatform {
         return true;
     }
     marshallArray(values) {
-        const quote = (v) => v === '' || v.match(/["{},]/) ? JSON.stringify(v) : v;
+        const quote = (v) => v === '' || v.match(/["{},\\]/) ? JSON.stringify(v) : v;
         return `{${values.map(v => quote('' + v)).join(',')}}`;
     }
     unmarshallArray(value) {

Versions

Dependency	Version
node	20.5.1
typescript	5.2.2
mikro-orm	5.8.4
postgres	15.4

[B4nan]

Working patch, can make a PR if this looks good:

Sure, as long as it does not break any existing tests, PR welcome! The change is looking good to me.