fix: fix null pointer exception on date array column comparison (#11532)

* fix: fix null pointer exception on date array column comparison

Follow up to https://github.com/typeorm/typeorm/pull/11269 which was
calling Array.map without validating if the array was null. Now only
normalize if both values (entity and database) are not null.

Closes: https://github.com/typeorm/typeorm/issues/11514

* clean test

src/persistence/SubjectChangedColumnsComputer.ts

@@ -1,9 +1,9 @@
-import { Subject } from "./Subject"
-import { DateUtils } from "../util/DateUtils"
 import { ObjectLiteral } from "../common/ObjectLiteral"
-import { OrmUtils } from "../util/OrmUtils"
 import { ApplyValueTransformers } from "../util/ApplyValueTransformers"
+import { DateUtils } from "../util/DateUtils"
 import { ObjectUtils } from "../util/ObjectUtils"
+import { OrmUtils } from "../util/OrmUtils"
+import { Subject } from "./Subject"
 
 /**
  * Finds what columns are changed in the subject entities.
@@ -81,8 +81,8 @@ export class SubjectChangedColumnsComputer {
                     if (value !== null && value !== undefined) return
                 }
                 let normalizedValue = entityValue
-                // normalize special values to make proper comparision
-                if (entityValue !== null) {
+                // if both values are not null, normalize special values to make proper comparision
+                if (entityValue !== null && databaseValue !== null) {
                     switch (column.type) {
                         case "date":
                             normalizedValue = column.isArray

test/github-issues/5967/entity/User.ts

@@ -17,4 +17,10 @@ export class User {
         default: "{}",
     })
     dates: Date[]
+
+    @Column("time without time zone", {
+        nullable: true,
+        array: true,
+    })
+    nullable_times: string[] | null
 }

test/github-issues/5967/issue-5967.ts

@@ -191,6 +191,72 @@ describe("github issues > #5967 @afterUpdate always says array/json field update
                     dates: valueAfter,
                 })
 
+                const updateQueries = logger.queries.filter((q) =>
+                    q.startsWith("UPDATE"),
+                )
+                expect(updateQueries).to.have.length(1)
+            }),
+        ))
+
+    it("should update a time array column when it goes from null to a value", () =>
+        Promise.all(
+            dataSources.map(async (dataSource) => {
+                const valueBefore = null
+                const valueAfter = ["12:00"]
+
+                const repository = dataSource.getRepository(User)
+
+                const logger = dataSource.logger as MemoryLogger
+                logger.clear()
+
+                const user = await repository.save({
+                    nullable_times: valueBefore,
+                })
+
+                const insertQueries = logger.queries.filter((q) =>
+                    q.startsWith("INSERT"),
+                )
+                expect(insertQueries).to.have.length(1)
+                logger.clear()
+
+                await repository.save({
+                    id: user.id,
+                    nullable_times: valueAfter,
+                })
+
+                const updateQueries = logger.queries.filter((q) =>
+                    q.startsWith("UPDATE"),
+                )
+                expect(updateQueries).to.have.length(1)
+            }),
+        ))
+
+    it("should update a time array column when it goes from a value to null", () =>
+        Promise.all(
+            dataSources.map(async (dataSource) => {
+                const valueBefore = ["12:00"]
+                const valueAfter = null
+
+                const repository = dataSource.getRepository(User)
+
+                const logger = dataSource.logger as MemoryLogger
+                logger.clear()
+
+                const user = await repository.save({
+                    nullable_times: valueBefore,
+                })
+
+                const insertQueries = logger.queries.filter((q) =>
+                    q.startsWith("INSERT"),
+                )
+                expect(insertQueries).to.have.length(1)
+                logger.clear()
+
+                await repository.save({
+                    id: user.id,
+                    nullable_times: valueAfter,
+                })
+
                 const updateQueries = logger.queries.filter((q) =>
                     q.startsWith("UPDATE"),
                 )