Crash when scrolling in the public rooms from Unified Search

[jeangb]

To reproduce (some steps might be unnecessary but I almost sure it crashes with them)

1. Hit the Rooms tab, then ROOM DIRECTORY section
2. Scroll down in the public rooms, more than the 20 firsts
3. Clear the cache from riot settings
4. Repeat 1. & 2.
5. Go in the People tab
6. Open the global search
7. From the global search, hit the People tab, than quickly return in the Rooms tab from the global search
8. Hit Browse directory
9. Scroll down quickly in the public rooms

Crash
https://github.com/matrix-org/riot-ios-rageshakes/issues/79

[jeangb]

Simpler steps:

1. Clear riot cache
2. Open the global search
3. Hit People tab from the global search then scroll down a bit the contact list
4. Quicky hit Rooms tab
5. Hit Browse directory
6. Scroll down quickly

[manuroe]

4744070802373897196 - 2017-06-23 12:30:11 +0000
Invalid update: invalid number of rows in section 0.  The number of rows contained in an existing section after the update (100) must be equal to the number of rows contained in that section before the update (60), plus or minus the number of rows inserted or deleted from that section (20 inserted, 0 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).
Application: Riot (im.vector.app)
Application version: 0.4.0 (r0.4.0)
Matrix SDK version: 0.8.0
Build: develop #1969
iPhone 10.3.2

Main thread: YES
(
	0   CoreFoundation                      0x0000000184e02ff8 <redacted> + 148
	1   libobjc.A.dylib                     0x0000000183864538 objc_exception_throw + 56
	2   CoreFoundation                      0x0000000184e02eb4 <redacted> + 0
	3   Foundation                          0x000000018589a720 <redacted> + 112
	4   UIKit                               0x000000018b112d98 <redacted> + 13224
	5   UIKit                               0x000000018b12bd5c <redacted> + 360
	6   Riot                                0x0000000100028054 Riot + 163924 -> __44-[DirectoryViewController triggerPagination]_block_invoke (in Riot) (DirectoryViewController.m:245)
	7   Riot                                0x0000000100084784 Riot + 542596 -> __51-[PublicRoomsDirectoryDataSource paginate:failure:]_block_invoke (in Riot) (PublicRoomsDirectoryDataSource.m:264)
	8   libdispatch.dylib                   0x0000000183cba9e0 <redacted> + 24
	9   libdispatch.dylib                   0x0000000183cba9a0 <redacted> + 16
	10  libdispatch.dylib                   0x0000000183cbf5e8 _dispatch_main_queue_callback_4CF + 996
	11  CoreFoundation                      0x0000000184db10c8 <redacted> + 12
	12  CoreFoundation                      0x0000000184daece4 <redacted> + 1572
	13  CoreFoundation                      0x0000000184cdeda4 CFRunLoopRunSpecific + 424
	14  GraphicsServices                    0x0000000186748074 GSEventRunModal + 100
	15  UIKit                               0x000000018af99058 UIApplicationMain + 208
	16  Riot                                0x0000000100041c14 Riot + 269332 -> main (in Riot) (main.m:30)
	17  libdyld.dylib                       0x0000000183ced59c <redacted> + 4
)