updated based on code review

Author: AidenCohen31

action.yml

@@ -34,7 +34,7 @@ inputs:
     required: false
     default: ''
   image_name:
-    description: 'name of docker image'
+    description: 'Name of the image to build, e.g. "opensciencegrid/software-base"'
     required: false
     default: ''
 
@@ -46,7 +46,7 @@ runs:
   - id: generate-image-name
     shell: bash
     run: |
-      if  [[ ${{ inputs.image_name }} != '' ]]; then
+      if  [[ -n ${{ inputs.image_name }} ]]; then
          IMAGE_NAME="${{ inputs.image_name }}"
       elif [[ -n "${{ inputs.name }}" ]]; then
         # A name was specified
@@ -62,7 +62,7 @@ runs:
          # grab the image name from the full context path instead
          IMAGE_NAME=${GITHUB_REPOSITORY%%/*}/$(basename ${{ inputs.context }})
       else
-        echo "${{ inputs.context }} is not a directory"
+        echo "No image_name provided and ${{ inputs.context }} is not a directory"
         exit 1
       fi
       echo "::set-output name=image::$IMAGE_NAME"