Fixed: some analyzers throw an exception when a definition of any assembly is not available.

ILSpy/TreeNodes/Analyzer/AnalyzedFieldAccessNode.cs

@@ -57,8 +57,9 @@ namespace ICSharpCode.ILSpy.TreeNodes.Analyzer
 			return FindReferences(MainWindow.Instance.AssemblyList.GetAssemblies(), ct);
 		}
 		
-		IEnumerable<SharpTreeNode> FindReferences(LoadedAssembly[] assemblies, CancellationToken ct)
+		IEnumerable<SharpTreeNode> FindReferences(IEnumerable<LoadedAssembly> assemblies, CancellationToken ct)
 		{
+			assemblies = assemblies.Where(asm => asm.AssemblyDefinition != null);
 			// use parallelism only on the assembly level (avoid locks within Cecil)
 			return assemblies.AsParallel().WithCancellation(ct).SelectMany((LoadedAssembly asm) => FindReferences(asm, ct));
 		}

ILSpy/TreeNodes/Analyzer/AnalyzedMethodUsedByTreeNode.cs

@@ -70,8 +70,9 @@ namespace ICSharpCode.ILSpy.TreeNodes.Analyzer
 			return FindReferences(MainWindow.Instance.AssemblyList.GetAssemblies(), ct);
 		}
 		
-		IEnumerable<SharpTreeNode> FindReferences(LoadedAssembly[] assemblies, CancellationToken ct)
+		IEnumerable<SharpTreeNode> FindReferences(IEnumerable<LoadedAssembly> assemblies, CancellationToken ct)
 		{
+			assemblies = assemblies.Where(asm => asm.AssemblyDefinition != null);
 			// use parallelism only on the assembly level (avoid locks within Cecil)
 			return assemblies.AsParallel().WithCancellation(ct).SelectMany((LoadedAssembly asm) => FindReferences(asm, ct));
 		}

ILSpy/TreeNodes/Analyzer/AnalyzedPropertyOverridesTreeNode.cs

@@ -54,8 +54,9 @@ namespace ICSharpCode.ILSpy.TreeNodes.Analyzer
 			return FindReferences(MainWindow.Instance.AssemblyList.GetAssemblies(), ct);
 		}
 
-		IEnumerable<SharpTreeNode> FindReferences(LoadedAssembly[] assemblies, CancellationToken ct)
+		IEnumerable<SharpTreeNode> FindReferences(IEnumerable<LoadedAssembly> assemblies, CancellationToken ct)
 		{
+			assemblies = assemblies.Where(asm => asm.AssemblyDefinition != null);
 			// use parallelism only on the assembly level (avoid locks within Cecil)
 			return assemblies.AsParallel().WithCancellation(ct).SelectMany((LoadedAssembly asm) => FindReferences(asm, ct));
 		}

ILSpy/TreeNodes/Analyzer/AnalyzerMethodOverridesTreeNode.cs

@@ -58,8 +58,9 @@ namespace ICSharpCode.ILSpy.TreeNodes.Analyzer
 			return FindReferences(MainWindow.Instance.AssemblyList.GetAssemblies(), ct);
 		}
 
-		IEnumerable<SharpTreeNode> FindReferences(LoadedAssembly[] assemblies, CancellationToken ct)
+		IEnumerable<SharpTreeNode> FindReferences(IEnumerable<LoadedAssembly> assemblies, CancellationToken ct)
 		{
+			assemblies = assemblies.Where(asm => asm.AssemblyDefinition != null);
 			// use parallelism only on the assembly level (avoid locks within Cecil)
 			return assemblies.AsParallel().WithCancellation(ct).SelectMany((LoadedAssembly asm) => FindReferences(asm, ct));
 		}