fix warning

Author: chuongmep

Test/SetOrginHatch.cs

@@ -68,15 +68,17 @@ public void setOriginHatch()
         using (Transaction tr2 = doc.TransactionManager.StartTransaction())
         {
             Entity ent = (Entity) tr2.GetObject(mHatchId, OpenMode.ForWrite);
-            if (ent != null)
             {
-                Hatch nHatch = ent as Hatch;
-                String hatchName = nHatch.PatternName;
+                Hatch? nHatch = ent as Hatch;
+                string? hatchName = nHatch?.PatternName;
                 Point2d setOrigin = new Point2d(6.698, 2.78);
-                nHatch.Origin = setOrigin;
-                nHatch.SetHatchPattern(HatchPatternType.PreDefined, hatchName);
-                nHatch.EvaluateHatch(true);
-                nHatch.Draw();
+                if (nHatch != null)
+                {
+                    nHatch.Origin = setOrigin;
+                    nHatch.SetHatchPattern(HatchPatternType.PreDefined, hatchName);
+                    nHatch.EvaluateHatch(true);
+                    nHatch.Draw();
+                }
             }
 
             tr2.Commit();

Test/TestCircle.cs

@@ -19,14 +19,18 @@ public void cmdCreateCricle()
         using (var tr = db.TransactionManager.StartTransaction())
         {
             var bt = tr.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
-            var ms = tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;
-            var circle = new Autodesk.AutoCAD.DatabaseServices.Circle();
-            Random ran = new Random();
-            int c = ran.Next(0, 100);
-            circle.Center = new Point3d(0, 10, 0);
-            circle.Radius = c;
-            ms.AppendEntity(circle);
-            tr.AddNewlyCreatedDBObject(circle, true);
+            if (bt != null)
+            {
+                var ms = tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;
+                var circle = new Autodesk.AutoCAD.DatabaseServices.Circle();
+                Random ran = new Random();
+                int c = ran.Next(0, 100);
+                circle.Center = new Point3d(0, 10, 0);
+                circle.Radius = c;
+                ms?.AppendEntity(circle);
+                tr.AddNewlyCreatedDBObject(circle, true);
+            }
+
             tr.Commit();
 
         }

Test/TestLine.cs

@@ -53,7 +53,7 @@ public void FindCmdDuplicatesCmd()
 
         {
             string asmPath = SelectAssembly();
-            if (asmPath == null) return;
+            if (string.IsNullOrEmpty(asmPath)) return;
             FindCmdDuplicates(asmPath);
         }
 
@@ -103,7 +103,7 @@ private string SelectAssembly()
             }
 
 
-            return null;
+            return String.Empty;
         }