fix: respect AbortSignal in run() - throw on pre-aborted and mid-poll abort

run() ignores AbortSignal in two ways:
1. If signal is already aborted before calling run(), the prediction
   starts anyway instead of throwing immediately
2. If signal becomes aborted during polling, run() cancels the
   prediction but returns the result instead of throwing AbortError

Now checks signal.aborted before starting the prediction and throws
AbortError after cancellation instead of silently returning output.
The cancel call is wrapped in catch to handle cases where the
prediction already completed on Replicate's servers.

Fixes #370

Author: ctonneslan

index.js

@@ -145,6 +145,13 @@ class Replicate {
   async run(ref, options, progress) {
     const { wait = { mode: "block" }, signal, ...data } = options;
 
+    // Throw immediately if signal is already aborted
+    if (signal?.aborted) {
+      const error = new Error("Aborted");
+      error.name = "AbortError";
+      throw error;
+    }
+
     const identifier = ModelVersionIdentifier.parse(ref);
 
     let prediction;
@@ -191,7 +198,10 @@ class Replicate {
     }
 
     if (signal && signal.aborted) {
-      prediction = await this.predictions.cancel(prediction.id);
+      await this.predictions.cancel(prediction.id).catch(() => {});
+      const error = new Error("Aborted");
+      error.name = "AbortError";
+      throw error;
     }
 
     // Call progress callback with the completed prediction object