Default result on intersection fix

deps/martinez-rueda-php/src/Algorithm.php

@@ -103,6 +103,10 @@ class Algorithm
                 $result = ($subject->ncontours() == 0) ? $clipping : $subject;
             }
 
+            if ($operation == self::OPERATION_INTERSECTION) {
+                $result = new Polygon([]);
+            }
+
             return $result;
         }
 
@@ -130,6 +134,10 @@ class Algorithm
                 }
             }
 
+            if ($operation == self::OPERATION_INTERSECTION) {
+                $result = new Polygon([]);
+            }
+
             return $result;
         }