Merge pull request #16 from capralifecycle/jlj/fix-slack-notify-action

fix: Slack notify action that tries response.json() on application/te…

slack-notify/action.mjs

@@ -28,20 +28,35 @@ const body = JSON.stringify({
 if (dryRun) {
   appendFileSync(process.env.GITHUB_OUTPUT, `payload=${body}\n`)
 } else {
-  const endpointUrl = incomingWebhookUrl || "https://slack.com/api/chat.postMessage"
+  const useIncomingWebhook = incomingWebhookUrl !== undefined
+  const endpointUrl = useIncomingWebhook ?  incomingWebhookUrl : "https://slack.com/api/chat.postMessage"
   const response = await fetch(endpointUrl, {
     method: "POST",
     body,
     headers: {
+      /* 
+      * Only set the Authorization header if we're not using webhook and bot token is defined
+      * Since there's a check above, there will under no circumstances be a situation where 
+      * useIncomingWebhook is true and the botToken-variable is defined
+      */
       ...(botToken && { "Authorization": `Bearer ${botToken}` }),
       "Content-Type": "application/json; charset=utf-8"
     }
   })
   if (!response.ok) {
     throw new Error(`Request failed with status ${response.status} ${response.statusText}`)
   }
-  const { ok, error } = await response.json()
-  if (!ok) {
-    throw new Error(`Request failed with error ${error}`)
+  /*
+  * Slack is using a different response scheme for incoming webhooks. Thereby,
+  * we only do fetch.then(response => resonse.json()) if messages was posted to the
+  * chat.postMessage-api. 
+  * 
+  * Error handling for incoming webhooks: https://api.slack.com/messaging/webhooks#handling_errors
+  */
+  if (!useIncomingWebhook) {
+    const { ok, error } = await response.json()
+    if (!ok) {
+      throw new Error(`Request failed with error ${error}`)
+    }
   }
 }