fix unhandled error (#138)

posthog-node/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 3.2.1 - 2023-12-15
+
+1. Fixes issue where a background refresh of feature flags could throw an unhandled error. It now emits to be detected by `.on('error', ...)`
+
 # 3.2.0 - 2023-12-05
 
 1. Fixes issues with Axios imports for non-node environments like Cloudflare workers

posthog-node/package.json

@@ -1,6 +1,6 @@
 {
   "name": "posthog-node",
-  "version": "3.2.0",
+  "version": "3.2.1",
   "description": "PostHog Node.js integration",
   "repository": "PostHog/posthog-node",
   "scripts": {

posthog-node/src/feature-flags.ts

@@ -37,6 +37,7 @@ type FeatureFlagsPollerOptions = {
   pollingInterval: number
   timeout?: number
   fetch?: (url: string, options: PostHogFetchOptions) => Promise<PostHogFetchResponse>
+  onError?: (error: Error) => void
 }
 
 class FeatureFlagsPoller {
@@ -53,6 +54,7 @@ class FeatureFlagsPoller {
   poller?: NodeJS.Timeout
   fetch: (url: string, options: PostHogFetchOptions) => Promise<PostHogFetchResponse>
   debugMode: boolean = false
+  onError?: (error: Error) => void
 
   constructor({
     pollingInterval,
@@ -75,6 +77,7 @@ class FeatureFlagsPoller {
     this.poller = undefined
     // NOTE: as any is required here as the AbortSignal typing is slightly misaligned but works just fine
     this.fetch = options.fetch || fetch
+    this.onError = options.onError
 
     void this.loadFeatureFlags()
   }
@@ -177,7 +180,7 @@ class FeatureFlagsPoller {
         if (e instanceof InconclusiveMatchError) {
           // do nothing
         } else if (e instanceof Error) {
-          console.error(`Error computing flag locally: ${flag.key}: ${e}`)
+          this.onError?.(new Error(`Error computing flag locally: ${flag.key}: ${e}`))
         }
         fallbackToDecide = true
       }
@@ -395,7 +398,7 @@ class FeatureFlagsPoller {
       // if an error that is not an instance of ClientError is thrown
       // we silently ignore the error when reloading feature flags
       if (err instanceof ClientError) {
-        throw err
+        this.onError?.(err)
       }
     }
   }

posthog-node/src/posthog-node.ts

@@ -56,6 +56,9 @@ export class PostHog extends PostHogCoreStateless implements PostHogNodeV1 {
         timeout: options.requestTimeout ?? 10000, // 10 seconds
         host: this.host,
         fetch: options.fetch,
+        onError: (err: Error) => {
+          this._events.emit('error', err)
+        },
       })
     }
     this.distinctIdHasSentFlagCalls = {}