The following error is logged when typing in Visual Studio for Mac 7.4.
An unhandled exception has occured. Terminating Visual Studio? False
System.NullReferenceException: Object reference not set to an instance of an object
at MonoDevelop.Ide.CodeCompletion.ParameterInformationWindow+<UpdateParameterInfoLocation>d__14.MoveNext () [0x0002b] in monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.CodeCompletion/ParameterInformationWindow.cs:109
On master this is handled with a null check:
mono/monodevelop@092db73
However MonoDevelop should be debugged to understand why the language server is causing a null reference exception here.