Prevent skipping dependency download when cache folder is empty

[wolfchkov]

Bug Report

If the initial module download fails but its directory is created, subsequent attempts will always result in a "package not found" error, with no retry attempted.

This can be easily reproduced: press Ctrl+C to cancel the download before kcl run finishes downloading the module, then run kcl run again.

1. Minimal reproduce step (Required)

➜  kcl test tests                              
downloading 'kcl-lang/k8s:1.31.2' from 'ghcr.io/kcl-lang/k8s:1.31.2'
^C

➜  kcl test tests          
package 'k8s:1.31.2' not found

2. What did you expect to see? (Required)

Since, the folder is empty (there is no kcl.mod file), the module should be downloaded without any error.

3. What did you see instead (Required)

The error:

package 'k8s:1.31.2' not found

4. What is your KCL components version? (Required)

kcl version 0.11.3