Fix crash when roomSummary is nil

[Velin92]

This PR fixes the following crash: element-hq/element-ios#7403

[codecov]

Codecov Report

Patch coverage: 20.37% and project coverage change: -0.09 ⚠️

Comparison is base (f52a4d2) 37.53% compared to head (8c05fab) 37.44%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1731      +/-   ##
===========================================
- Coverage    37.53%   37.44%   -0.09%     
===========================================
  Files          612      612              
  Lines        96235    96266      +31     
  Branches     41603    41613      +10     
===========================================
- Hits         36119    36046      -73     
- Misses       59041    59163     +122     
+ Partials      1075     1057      -18     

Impacted Files	Coverage Δ
.../Background/Store/MXSyncResponseStoreManager.swift	0.00% <0.00%> (ø)
MatrixSDK/Data/MXRoom.m	37.86% <0.00%> (ø)
...List/Common/MXBreadcrumbsRoomListDataFetcher.swift	0.00% <0.00%> (ø)
.../Data/RoomList/Common/MXRoomListDataSortable.swift	79.06% <0.00%> (ø)
...mList/CoreData/MXCoreDataRoomListDataFetcher.swift	59.71% <0.00%> (ø)
MatrixSDK/MXSession.m	39.72% <ø> (-0.15%)	⬇️
MatrixSDK/Space/MXSpaceService.swift	42.31% <0.00%> (ø)
MatrixSDK/VoIP/MXCall.m	0.00% <0.00%> (ø)
MatrixSDKTests/MXBackgroundSyncServiceTests.swift	1.84% <0.00%> (ø)
MatrixSDKTests/MXLazyLoadingTests.m	0.00% <0.00%> (ø)
... and 27 more

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[stefanceriu]

Looks good to me except for the inline comments

[stefanceriu]

lgtm! 👍