feat: Require both inputs to be set on action (#3554)

Came as a feature request from @untitaker and I think it makes a lot of sense

---------

Co-authored-by: Hubert Deng <hubert.deng@sentry.io>

Author: BYK

action.yaml

@@ -13,12 +13,22 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - name: Configure to use the test image
-      if: inputs.project_name && inputs.image_url
+    - name: Validate inputs and configure test image
       shell: bash
+      env:
+        PROJECT_NAME: ${{ inputs.project_name }}
+        IMAGE_URL: ${{ inputs.image_url }}
       run: |
-        image_var=$(echo ${{ inputs.project_name }}_IMAGE | tr '[:lower:]' '[:upper:]')
-        echo "${image_var}=${{ inputs.image_url }}" >> ${{ github.action_path }}/.env
+        if [[ -n "$PROJECT_NAME" && -n "$IMAGE_URL" ]]; then
+          image_var=$(echo "${PROJECT_NAME}_IMAGE" | tr '[:lower:]' '[:upper:]')
+          echo "${image_var}=$IMAGE_URL" >> ${{ github.action_path }}/.env
+        elif [[ -z "$PROJECT_NAME" && -z "$IMAGE_URL" ]]; then
+          echo "No project name and image URL set. Skipping image configuration."
+        else
+          echo "You must set both project_name and image_url or unset both."
+          echo "project_name: $PROJECT_NAME, image_url: $IMAGE_URL"
+          exit 1
+        fi
 
     - name: Setup dev environment
       shell: bash