How to reproduce:
1. Open the user's attached project
2. Build the project for IL2CPP
3. Observe the Console

Expected result: There are no visible errors present
Actual result: Multiple errors appear in the Console

Reproducible with: 2019.4.29f1, 2020.3.15f2, 2021.1.16f1, 2021.2.0b6, 2022.1.0a4

Notes:
- The issue doesn't reproduce when the Scripting Backend is set to Mono
- In 2019.4 and 2020.3 the following error appears in the Console:
Exception: IL2CPP error (no further information about what managed code was being converted is available)
System.InvalidCastException: Unable to cast object of type 'Mono.Cecil.MethodReference' to type 'Mono.Cecil.GenericInstanceMethod'.
at Unity.IL2CPP.Metadata.PerAssemblyCodeMetadataWriter.HandleRgctxKeyNotFoundException(ReadOnlyContext context, RGCTXEntry rgctxEntry, KeyNotFoundException e)
at Unity.IL2CPP.Metadata.PerAssemblyCodeMetadataWriter.<>c__DisplayClass8_0.<WriteRGCTXValues>b__0(RGCTXEntry rgctxEntry)
at System.Linq.Enumerable.SelectIListIterator`2.ToArray()
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Unity.IL2CPP.CodeWriters.CodeWriterExtensions.WriteArrayInitializer(ICodeWriter writer, String type, String variableName, IEnumerable`1 values, Boolean externArray, Boolean nullTerminate)
at Unity.IL2CPP.Metadata.PerAssemblyCodeMetadataWriter.WriteRGCTXValues(SourceWritingContext context, ICppCodeWriter writer, GenericContextCollection genericContextCollection, List`1 res)
at Unity.IL2CPP.Metadata.PerAssemblyCodeMetadataWriter.Write(SourceWritingContext context, AssemblyDefinition assembly, GenericContextCollection genericContextCollection, String assemblyMetadataRegistrationVarName, String codeRegistrationVarName)
at Unity.IL2CPP.AssemblyConversion.SecondaryWrite.Steps.PerAssembly.WritePerAssemblyCodeMetadata.ProcessItem(GlobalWriteContext context, AssemblyDefinition item)
at Unity.IL2CPP.AssemblyConversion.Steps.Base.ScheduledItemsStepFuncWithContinueAction`3.WorkerWrapper(WorkItemData`3 workerData)
at Unity.IL2CPP.Contexts.Scheduling.PhaseWorkScheduler`1.ContinueWithResultsWorkItem`4.InvokeWorker(Object context, Int32 uniqueId)
at Unity.IL2CPP.Contexts.Scheduling.PhaseWorkScheduler`1.BaseContinueWorkItem`2.Invoke(Object context, Int32 uniqueId)
at Unity.IL2CPP.Contexts.Scheduling.PhaseWorkScheduler`1.WorkerLoop(Object data)
UnityEditorInternal.Runner.RunProgram (UnityEditor.Utils.Program p, System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action`1[T] setupStartInfo) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditorInternal.IL2CPPBuilder.RunIl2CppWithArguments (System.Collections.Generic.List`1[T] arguments, System.Action`1[T] setupStartInfo) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditorInternal.IL2CPPBuilder.ConvertPlayerDlltoCpp (UnityEditor.Il2Cpp.Il2CppBuildPipelineData data) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditorInternal.IL2CPPBuilder.Run () (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String stagingAreaData, UnityEditorInternal.IIl2CppPlatformProvider platformProvider, System.Action`1[T] modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry) (at <44c3723143904fb88deebc993c7bb491>:0)
DesktopStandalonePostProcessor.RunIL2CPP (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditorInternal.IIl2CppPlatformProvider il2cppPlatformProvider, System.Collections.Generic.List`1[T] cppPlugins) (at <44c3723143904fb88deebc993c7bb491>:0)
DesktopStandalonePostProcessor.SetupStagingArea (UnityEditor.Modules.BuildPostProcessArgs args, System.Collections.Generic.HashSet`1[T] filesToNotOverwrite) (at <44c3723143904fb88deebc993c7bb491>:0)
DesktopStandalonePostProcessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at <44c3723143904fb88deebc993c7bb491>:0)
Rethrow as BuildFailedException: Exception of type 'UnityEditor.Build.BuildFailedException' was thrown.
DesktopStandalonePostProcessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditor.Modules.DefaultBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditor.BuildProperties& outProperties) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEditor.PostprocessBuildPlayer.Postprocess (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget target, System.String installPath, System.String companyName, System.String productName, System.Int32 width, System.Int32 height, UnityEditor.BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport report) (at <44c3723143904fb88deebc993c7bb491>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)

- In 2021.2 and above the error changes to:
BuildFailedException: Incremental Player build failed!
UnityEditor.Modules.BeeBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args) (at <991b2b0c3b89400a982fc1788acb93dc>:0)
UnityEditor.Modules.DefaultBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditor.BuildProperties& outProperties) (at <991b2b0c3b89400a982fc1788acb93dc>:0)
UnityEditor.WindowsStandalone.WinPlayerPostProcessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditor.BuildProperties& outProperties) (at C:/buildslave/unity/build/PlatformDependent/WinPlayer/Extensions/Managed/WinPlayerPostProcessor.cs:33)
UnityEditor.PostprocessBuildPlayer.Postprocess (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget target, System.Int32 subtarget, System.String installPath, System.String companyName, System.String productName, System.Int32 width, System.Int32 height, UnityEditor.BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport report) (at <991b2b0c3b89400a982fc1788acb93dc>:0)
UnityEditor.BuildPlayerWindow:BuildPlayerAndRun()