How to reproduce:
1. Open the attached "TilesCrash" project and "scene"
2. Enter playmode and click your right mouse button onto Terrain
3. Click your left mouse button on Terrain
4. Wait for the NavMesh errors to be output in the console ('"Resume" can only be called on an active agent that has been placed on a NavMesh') and navigate with W,A,S,D keys around the Terrain
5. Once the errors are stopped being output (or there are more of them than 999), exit playmode, the crash should occur in a few seconds (repeat the 2nd-5th steps until the crash occurs, usually it occurs during second/third time on playmode or after re-opening the project)

Result - Crash occurs on:
0x00000001409D6AFE (Unity) ClassifyTilesToRemoveAndCompute
0x00000001409DD8FB (Unity) ScheduleNavMeshDataUpdate
0x00000001409DDA9C (Unity) NavMeshBuildOperation::Schedule
0x0000000141080669 (Unity) JobQueue::Exec
0x000000014107F659 (Unity) JobQueue::Steal

Reproducible with - 2017.3.0b3, 2017.2.0f2, 2017.1.1p4, 5.6.3p4

Fixed in - 2018.2.0a2