fix: skip port deletion when instances have no port (#779)

diff --git a/images/base/Earthfile b/images/base/Earthfile
new file mode 100644
index 0000000..c075abc
--- /dev/null
+++ b/images/base/Earthfile
@@ -0,0 +1,4 @@
+VERSION 0.7
+
+image:
+  FROM ubuntu:jammy