Fix crash in Change Procedure to Function quick fix

Author: Hosch250

RetailCoder.VBE/Inspections/ProcedureShouldBeFunctionInspectionResult.cs

@@ -77,8 +77,12 @@ private void UpdateSignature()
 
             var newArgText = argText.Contains("ByRef ") ? argText.Replace("ByRef ", "ByVal ") : "ByVal " + argText;
 
+            var asTypeClause = _argQualifiedContext.Context.asTypeClause() != null
+                ? _argQualifiedContext.Context.asTypeClause().GetText()
+                : "As Variant";
+
             var newFunctionWithoutReturn = subStmtText.Insert(subStmtText.IndexOf(argListText, StringComparison.Ordinal) + argListText.Length,
-                                                              " " + _argQualifiedContext.Context.asTypeClause().GetText())
+                                                              " " + asTypeClause)
                                                       .Replace("Sub", "Function")
                                                       .Replace(argText, newArgText);
 

RubberduckTests/Inspections/ProcedureShouldBeFunctionInspectionTests.cs

@@ -330,6 +330,46 @@ public void ProcedureShouldBeFunction_QuickFixWorks()
             Assert.AreEqual(expectedCode, module.Lines());
         }
 
+        [TestMethod]
+        [TestCategory("Inspections")]
+        public void ProcedureShouldBeFunction_QuickFixWorks_NoAsTypeClauseInParam()
+        {
+            const string inputCode =
+@"Private Sub Foo(ByRef arg1)
+End Sub";
+
+            const string expectedCode =
+@"Private Function Foo(ByVal arg1) As Variant
+    Foo = arg1
+End Function";
+
+            //Arrange
+            var settings = new Mock<IGeneralConfigService>();
+            var config = GetTestConfig();
+            settings.Setup(x => x.LoadConfiguration()).Returns(config);
+
+            var builder = new MockVbeBuilder();
+            VBComponent component;
+            var vbe = builder.BuildFromSingleStandardModule(inputCode, out component);
+            var project = vbe.Object.VBProjects.Item(0);
+            var module = project.VBComponents.Item(0).CodeModule;
+            var mockHost = new Mock<IHostApplication>();
+            mockHost.SetupAllProperties();
+            var parser = MockParser.Create(vbe.Object, new RubberduckParserState(vbe.Object, new Mock<ISinks>().Object));
+
+            parser.Parse(new CancellationTokenSource());
+            if (parser.State.Status >= ParserState.Error) { Assert.Inconclusive("Parser Error"); }
+
+            var inspection = new ProcedureCanBeWrittenAsFunctionInspection(parser.State);
+            var inspector = new Inspector(settings.Object, new IInspection[] { inspection });
+
+            var inspectionResults = inspector.FindIssuesAsync(parser.State, CancellationToken.None).Result;
+
+            inspectionResults.First().QuickFixes.First().Fix();
+
+            Assert.AreEqual(expectedCode, module.Lines());
+        }
+
         [TestMethod]
         [TestCategory("Inspections")]
         public void ProcedureShouldBeFunction_QuickFixWorks_DoesNotInterfereWithBody()