Fix/wiki not initialized issue (#50)

* Adds check for faild cloning and improves docs

* Adds error and exit 1 for push as well

README.md

@@ -8,7 +8,9 @@ For rendering, it uses an instance of the [PlantUML Java app](https://plantuml.c
 
 ## Usage
 
-First you need to create an authentication token that gives this action access to your wiki. This is neccessary since `${{ secrets.GITHUB_TOKEN }}`, which is automatically available within workflows, doesn't work with the wiki.
+First make sure that your wiki is initalized. This means that you need to create at least one page in the wiki before this action can push the rendered diagrams to it. Otherwise the action will fail.
+
+Then you need to create an authentication token that gives this action access to your wiki. This is neccessary since `${{ secrets.GITHUB_TOKEN }}`, which is automatically available within workflows, doesn't work with the wiki.
 
 Follow [this documentation](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) to create the token. Then follow [this documentation](https://docs.github.com/en/actions/configuring-and-managing-workflows/creating-and-storing-encrypted-secrets) to add the secret to your organization. Name the secret `WIKI_TOKEN`.
 

entrypoint.sh

@@ -71,6 +71,11 @@ rm -r "${GITHUB_WORKSPACE}/artifacts_repo"
 
 echo "=> Cloning wiki repository ..."
 git clone $artifacts_repo "${GITHUB_WORKSPACE}/artifacts_repo"
+if [ $? -gt 0 ]; then
+    echo "   ERROR: Could not clone repo."
+    echo "   Note: you need to initialize the wiki by creating at least one page before you can use this action!"
+    exit 1
+fi
 
 echo "=> Moving generated files to /${artifacts_upload_dir} in wiki repo ..."
 mkdir -p "${GITHUB_WORKSPACE}/artifacts_repo/${artifacts_upload_dir}"
@@ -85,6 +90,10 @@ git add .
 if git commit -m"Auto-generated PlantUML diagrams"; then
     echo "=> Pushing artifacts ..."
     git push
+    if [ $? -gt 0 ]; then
+    echo "   ERROR: Could not push to repo."
+    exit 1
+fi
 else
     echo "(i) Nothing changed since previous build. The wiki is already up to date and therefore nothing is being pushed."
 fi