feat: Use elaborate errors value from API response if available

src/main.ts

@@ -1,5 +1,6 @@
 import { getInput, info, setFailed, warning } from '@actions/core';
 import { getOctokit } from '@actions/github';
+import { RequestError } from '@octokit/request-error';
 import {
     CommitStatusState,
     getCommitHash,
@@ -20,6 +21,10 @@ interface Inputs {
     context?: string;
 }
 
+interface ValidationFailedError {
+    errors: object | string;
+}
+
 function getInputs(): Inputs {
     const token = getInput('token', { required: true });
     const state = validateCommitStatusState(getInput('status', { required: true }));
@@ -66,7 +71,18 @@ async function run(): Promise<void> {
             context: inputs.context,
         });
     } catch (error) {
-        setFailed((error as Error).message);
+        let foundMoreElaborateError = false;
+        const reqError = error as RequestError;
+        if (reqError.response !== undefined) {
+            const errorData = reqError.response.data as ValidationFailedError;
+            if (typeof errorData.errors === 'string') {
+                foundMoreElaborateError = true;
+                setFailed(errorData.errors);
+            }
+        }
+        if (!foundMoreElaborateError) {
+            setFailed((error as Error).message);
+        }
     }
 }