From a98f3af2e1bea648e51a184897c42ddb75d1bb8b Mon Sep 17 00:00:00 2001
From: Kevin Andersen <k.andersen@lego.com>
Date: Fri, 12 Apr 2019 13:56:29 -0400
Subject: [PATCH] Added a special case in motorOnForRotation() to avoid hanging
 blocks if power is 0

---
 src/extensions/scratch3_boost/index.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/extensions/scratch3_boost/index.js b/src/extensions/scratch3_boost/index.js
index b46b546f5..87f1937f1 100644
--- a/src/extensions/scratch3_boost/index.js
+++ b/src/extensions/scratch3_boost/index.js
@@ -1695,6 +1695,8 @@ class Scratch3BoostBlocks {
         const promises = motors.map(portID => {
             const motor = this._peripheral.motor(portID);
             if (motor) {
+                // to avoid a hanging block if power is 0, return an immediately resolving promise.
+                if (motor.power === 0) return new Promise(resolve => resolve());
                 return new Promise(resolve => {
                     motor.turnOnForDegrees(degrees, sign);
                     motor.pendingPromiseFunction = resolve;