Fix stop not working for DevServer starter

buildSrc/src/steamwar.devserver.gradle

@@ -109,11 +109,11 @@ class DevServer extends DefaultTask {
         Finalizer() {
             super()
             doLast {
-                running = false
                 if (processInput != null) {
                     processInput.write(template.endsWith("Velocity") ? "end\n" : "stop\n")
                     processInput.flush()
                 }
+                running = false
             }
         }
     }
@@ -245,10 +245,12 @@ class DevServer extends DefaultTask {
                 processInput.newLine()
                 processInput.flush()
             }
-            processInput.close()
         }).start()
 
         process.waitFor()
+        if (processInput != null) {
+            processInput.close()
+        }
         processInput = null
         running = false
     }