fix: error comparing changes from fork PR's

action.yml

@@ -61,6 +61,10 @@ inputs:
     description: 'Specify a base ref used for comparing changes, when `include-deleted-files` is set to `true`'
     required: false
     default: ${{ github.base_ref }}
+  head-repo-fork:
+    description: 'Specify a boolean indicating a PR from a fork is used for comparing changes, when `include-deleted-files` is set to `true`'
+    required: false
+    default: ${{ github.event.pull_request.head.repo.fork }}
   sha:
     description: 'Specify a current commit SHA used for comparing changes, when `include-deleted-files` is set to `true`'
     required: true

src/main.ts

@@ -64,6 +64,7 @@ export async function run(): Promise<void> {
     required: true
   })
   const baseRef = core.getInput('base-ref', {required: false})
+  const headRepoFork = core.getBooleanInput('head-repo-fork', {required: false})
   const sha = core.getInput('sha', {required: includeDeletedFiles})
   const baseSha = core.getInput('base-sha', {required: includeDeletedFiles})
 
@@ -197,7 +198,7 @@ export async function run(): Promise<void> {
         baseSha,
         sha,
         cwd: workingDirectory,
-        diff: !baseRef ? '..' : '...'
+        diff: !baseRef || headRepoFork ? '..' : '...'
       })
     )
   }