shutdown and teardown fixes + incoming connection handler

main/src/test/java/IntersectionProcessTest.java

@@ -97,11 +97,17 @@ public class IntersectionProcessTest {
         Files.writeString(configFile, configContent);
     }
 
-    // cleanup after tests
     @AfterEach
     public void tearDown() {
         if (intersectionProcess != null) {
-            intersectionProcess.shutdown();
+            try {
+                // Only shutdown if still running
+                intersectionProcess.shutdown();
+            } catch (Exception e) {
+                System.err.println("Error in tearDown: " + e.getMessage());
+            } finally {
+                intersectionProcess = null;
+            }
         }
     }