JQL functions error - when a Test Execution have a test run of a test that has been deleted

When we have Test Execution with a link to a a Test that have been deleted, then the JQL functions doesn't return any tests , even if the Test Execution does have relation to Tests that still exists.

Example: TESTEXEC-X1 links to TEST-1, TEST-2 (DELETED), TEST-3

then jql function issuetype = 'Test' and issue in testExecutionTests('TESTEXEC-X1') returns nothing when it should return TEST-1 and TEST-3