Fix ESLint workflow to only lint existing files

- Filter out deleted files from linting process
- Prevents ESLint errors when files are removed in PR
- Fixes jQuery upgrade PR linting failure

Author: Anshumancanrock

.github/workflows/linter.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Get changed JavaScript files
         id: get_files
         run: |
-          CHANGED_FILES=$(git diff --name-only ${{ github.event.pull_request.base.sha }}..${{ github.event.pull_request.head.sha }} -- '*.js')
+          CHANGED_FILES=$(git diff --name-only ${{ github.event.pull_request.base.sha }}..${{ github.event.pull_request.head.sha }} -- '*.js' | xargs -I {} sh -c 'test -f "{}" && echo "{}"')
           echo "files<<EOF" >> $GITHUB_ENV
           echo "$CHANGED_FILES" >> $GITHUB_ENV
           echo "EOF" >> $GITHUB_ENV
@@ -38,4 +38,8 @@ jobs:
         run: |
           echo "Linting the following files:"
           echo "$files"
-          echo "$files" | xargs npx eslint
+          if [ -n "$files" ]; then
+            echo "$files" | xargs npx eslint
+          else
+            echo "No existing JavaScript files to lint."
+          fi