Fix NullReferenceException for class type

Engine/Helper.cs

@@ -1094,7 +1094,7 @@ public string GetTypeFromMemberExpressionAst(MemberExpressionAst memberAst, Ast
                 if (details != null && classes != null)
                 {
                     // Get the class that corresponds to the name of the type (if possible)
-                    psClass = classes.FirstOrDefault(item => String.Equals(item.Name, details.Type.FullName, StringComparison.OrdinalIgnoreCase));
+                    psClass = classes.FirstOrDefault(item => String.Equals(item.Name, details.Type?.FullName, StringComparison.OrdinalIgnoreCase));
                 }
 
 #endif

Tests/Engine/InvokeScriptAnalyzer.tests.ps1

@@ -630,5 +630,35 @@ Describe "Test -EnableExit Switch" {
                 $warnings.RuleName | Should -Be 'TypeNotFound'
             }
         }
+
+        Describe "Handles static Singleton (issue 1182)" {
+            $scriptDefinition = @'
+                enum LogLevel
+                {
+                    Error
+                    Information
+                    Verbose
+                    Debug
+                }
+
+                class Logger
+                {
+                    static [Logger] $instance
+                }
+
+                function Write-Log
+                {
+                    [CmdletBinding()]
+                    param(
+                        [LogLevel] $LogLevel
+                    )
+
+                    $logger.WriteLog($LogLevel, "Hello")
+                }
+'@
+            It "Does not throw or return diagnostic record" {
+                Invoke-ScriptAnalyzer -ScriptDefinition $scriptDefinition -ErrorAction Stop | Should -BeNullOrEmpty
+            }
+        }
     }
 }