System.NullReferenceException: Object reference not set to an instance of an object.

[megahirt]

awa-flex

System.NullReferenceException: Object reference not set to an instance of an object.
  at LfMerge.Core.DataConverters.ConvertLcmToMongoLexicon.LcmWsToLfWs () [0x00048] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge.Core/DataConverters/ConvertLcmToMongoLexicon.cs:598
  at LfMerge.Core.DataConverters.ConvertLcmToMongoLexicon..ctor (LfMerge.Core.ILfProject lfProject, LfMerge.Core.Logging.ILogger logger, LfMerge.Core.MongoConnector.IMongoConnection connection, SIL.Progress.IProgress progress, LfMerge.Core.MongoConnector.MongoProjectRecordFactory projectRecordFactory) [0x00079] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge.Core/DataConverters/ConvertLcmToMongoLexicon.cs:65
  at LfMerge.Core.Actions.TransferLcmToMongoAction.DoRun (LfMerge.Core.ILfProject project) [0x00104] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge.Core/Actions/TransferLcmToMongoAction.cs:64
  at LfMerge.Core.Actions.Action.Run (LfMerge.Core.ILfProject project) [0x0010d] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge.Core/Actions/Action.cs:142
  at LfMerge.Core.Actions.SynchronizeAction.DoRun (LfMerge.Core.ILfProject project) [0x0038e] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge.Core/Actions/SynchronizeAction.cs:182
  at LfMerge.Core.Actions.Action.Run (LfMerge.Core.ILfProject project) [0x0010d] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge.Core/Actions/Action.cs:142
  at LfMerge.Program.RunAction (System.String projectCode, LfMerge.Core.Actions.ActionNames currentAction) [0x000f4] in /build/lfmerge-7000072-8UUe80/lfmerge-7000072-2.0.55.21/src/LfMerge/Program.cs:128 

[josephmyers]

Not sure what exactly was null in this method, as the code has changed since the stacktrace. We could try to get the DLL's for v2.0.55.21 and look at the decompile, or we could null-proof the roughly 15 potentials in the method.

[josephmyers]

@rmunn Chris informed me of the multiple branches I needed to search that could apply to the stacktrace. I searched master, live, and fieldworks8-live, and none of them had a line 598 that could obviously throw a NullReferenceException. Any ideas on how to identify the correct line?

[megahirt]

The assumption here is that this is FW9 code since the method is named "LcmWsToLfWs()". If it was FW8 code I assume it would have been named "FdoWsToLFWs()" or something similar.

So, we are looking at a NullReferenceException happening somewhere in the LcmWsToLfWs() method:

		private Dictionary<string, LfInputSystemRecord> LcmWsToLfWs()
		{
			// Using var here so that we'll stay compatible with both FW 8 and 9 (the type of these two lists changed between 8 and 9).
			var vernacularWSList = ServiceLocator.LanguageProject.CurrentVernacularWritingSystems;
			var analysisWSList = ServiceLocator.LanguageProject.CurrentAnalysisWritingSystems;

			var lfWsList = new Dictionary<string, LfInputSystemRecord>();
			foreach (var LcmWs in ServiceLocator.LanguageProject.AllWritingSystems)
			{
				var lfWs = new LfInputSystemRecord()
				{
					//These are for current libpalaso with SIL Writing Systems.
					// TODO: handle legacy WS definition
					Abbreviation = LcmWs.Abbreviation,
					IsRightToLeft = LcmWs.RightToLeftScript,
					LanguageName = LcmWs.LanguageName,
					#if FW8_COMPAT
					Tag = LcmWs.Id,
					#else
					Tag = LcmWs.LanguageTag,
					#endif
					VernacularWS = vernacularWSList.Contains(LcmWs),
					AnalysisWS = analysisWSList.Contains(LcmWs)
				};

				#if FW8_COMPAT
				lfWsList[LcmWs.Id] = lfWs;
				#else
				lfWsList[LcmWs.LanguageTag] = lfWs;
				#endif
			}
			return lfWsList;
		}

@josephmyers A null reference exception means that the code is trying to access a data property on a non-existent object, correct?

[megahirt]

Since this issue occurred a long time ago, we need to re-verify that this is still a problem.

@josephmyers TODO:

• verify that awa-flex is still on HOLD
• if still on HOLD, take it off HOLD and re-do the S/R.
• If the error persists, then debug it.