fix(linter): handle no changed files context

Signed-off-by: Emilien Escalle <emilien.escalle@escemi.com>

Author: neilime

.github/workflows/linter.yml

@@ -156,8 +156,8 @@ jobs:
       - id: get-files-to-lint
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         env:
-          CHANGED_FILES: ${{ toJSON(steps.changed-files.outputs.all_changed_and_modified_files) }};
-          ACTION_FILES_INPUT: ${{ toJSON(inputs.action-files) }}
+          CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_and_modified_files && toJSON(steps.changed-files.outputs.all_changed_and_modified_files) }}
+          ACTION_FILES_INPUT: ${{ inputs.action-files && toJSON(inputs.action-files) }}
         with:
           script: |
             const fs = require("node:fs");
@@ -166,7 +166,7 @@ jobs:
             const changedFiles = process.env.CHANGED_FILES;
 
             let actionFiles = [];
-            if (changedFiles !== null) {
+            if (changedFiles) {
               actionFiles = changedFiles.split(" ").filter(file => file && fs.existsSync(file));
             } else {
               const actionFilesInput = process.env.ACTION_FILES_INPUT;