diff --git a/src/input-providers/artifact-provider.ts b/src/input-providers/artifact-provider.ts
index f91a002..5222bbc 100644
--- a/src/input-providers/artifact-provider.ts
+++ b/src/input-providers/artifact-provider.ts
@@ -1,6 +1,6 @@
 import * as core from '@actions/core'
 import * as github from '@actions/github'
-import {GitHub} from '@actions/github/lib/utils.js'
+import {GitHub} from '@actions/github/lib/utils'
 
 import Zip from 'adm-zip'
 import picomatch from 'picomatch'
@@ -8,6 +8,11 @@ import picomatch from 'picomatch'
 import {FileContent, InputProvider, ReportInput} from './input-provider.js'
 import {downloadArtifact, listFiles} from '../utils/github-utils.js'
 
+type WorkflowRunArtifact = {
+  id: number
+  name: string
+}
+
 export class ArtifactProvider implements InputProvider {
   private readonly artifactNameMatch: (name: string) => boolean
   private readonly fileNameMatch: (name: string) => boolean
@@ -50,10 +55,10 @@ export class ArtifactProvider implements InputProvider {
   async load(): Promise<ReportInput> {
     const result: ReportInput = {}
 
-    const allArtifacts = await this.octokit.paginate(this.octokit.rest.actions.listWorkflowRunArtifacts, {
+    const allArtifacts = (await this.octokit.paginate(this.octokit.rest.actions.listWorkflowRunArtifacts, {
       ...github.context.repo,
       run_id: this.runId
-    })
+    })) as WorkflowRunArtifact[]
 
     if (allArtifacts.length === 0) {
       core.warning(`No artifacts found in run ${this.runId}`)
diff --git a/src/main.ts b/src/main.ts
index 2734ee8..888fd73 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,6 +1,6 @@
 import * as core from '@actions/core'
 import * as github from '@actions/github'
-import {GitHub} from '@actions/github/lib/utils.js'
+import {GitHub} from '@actions/github/lib/utils'
 
 import {ArtifactProvider} from './input-providers/artifact-provider.js'
 import {LocalFileProvider} from './input-providers/local-file-provider.js'
diff --git a/src/utils/github-utils.ts b/src/utils/github-utils.ts
index 74b2d51..eafeb4e 100644
--- a/src/utils/github-utils.ts
+++ b/src/utils/github-utils.ts
@@ -3,7 +3,7 @@ import {pipeline} from 'stream/promises'
 import {Readable, Transform} from 'stream'
 import * as core from '@actions/core'
 import * as github from '@actions/github'
-import {GitHub} from '@actions/github/lib/utils.js'
+import {GitHub} from '@actions/github/lib/utils'
 import type {PullRequest, WorkflowRunEvent} from '@octokit/webhooks-types'
 
 export function getCheckRunContext(): {sha: string; runId: number} {
@@ -125,7 +125,11 @@ async function listGitTree(octokit: InstanceType<typeof GitHub>, sha: string, pa
     if (tr.type === 'blob') {
       result.push(file)
     } else if (tr.type === 'tree' && truncated) {
-      const files = await listGitTree(octokit, tr.sha as string, `${file}/`)
+      if (!tr.sha) {
+        core.warning(`Skipping tree ${file}: missing SHA`)
+        continue
+      }
+      const files = await listGitTree(octokit, tr.sha, `${file}/`)
       result.push(...files)
     }
   }