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What version of drizzle-orm are you using?

0.45.2

What version of drizzle-kit are you using?

0.31.10

Other packages

No response

Describe the Bug

What is the undesired behavior?
drizzle-kit pull crashes with a TypeError: Cannot read properties of null (reading 'camelCase') when introspecting a MySQL 8+ database that contains a unique functional/expression index.

In MySQL 8, when an index is created using an expression (e.g., CREATE UNIQUE INDEX idx ON table ((CASE WHEN col = 1 THEN 1 ELSE NULL END))), the COLUMN_NAME field in INFORMATION_SCHEMA.STATISTICS returns NULL. Instead, the actual expression is stored in the EXPRESSION column.
Currently, mysqlSerializer.ts unconditionally pushes COLUMN_NAME into the index constraints. Later, during TS generation in introspect-mysql.ts, casing(null) is called, crashing the CLI.

What are the steps to reproduce?
I have created a minimal reproduction repository for this issue:
[Replicated error]

(https://github.com/danielcuque/mysql_drizzle)

1. Clone the repo and run pnpm install
2. Run pnpm run db:up to start the MySQL container.
3. Run pnpm run repro:index (which targets a table with a functional index).
4. (Assuming the silent crash bug is patched locally) You will see the TypeError originating from createTableUniques in introspect-mysql.ts.

What is the desired result?
Drizzle should extract the EXPRESSION column from INFORMATION_SCHEMA.STATISTICS when COLUMN_NAME is null. It should flag these columns in the internals object, and the TS generators should output them wrapped in sql\...`` instead of crashing.