From 1355f59df2dda5a5dee62bfa3f2d4dbfa240119b Mon Sep 17 00:00:00 2001
From: David Glasser <glasser@meteor.com>
Date: Wed, 10 Sep 2014 19:49:23 -0700
Subject: [PATCH] Change a "shouldn't happen" into a thrown Error

---
 packages/constraint-solver/resolver-state.js | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/packages/constraint-solver/resolver-state.js b/packages/constraint-solver/resolver-state.js
index e995a48333..5897a03ad9 100644
--- a/packages/constraint-solver/resolver-state.js
+++ b/packages/constraint-solver/resolver-state.js
@@ -123,10 +123,9 @@ _.extend(ResolverState.prototype, {
 
     // Does adding this choice break some constraints we already have?
     if (!self.isSatisfied(uv)) {
-      // XXX improve error
-      self.error = "conflict: " + uv.toString({removeUnibuild: true}) +
-        " can't be chosen";
-      return self;
+      // This shouldn't happen: all calls to addChoice should occur based on
+      // choosing it from a list of satisfied alternatives.
+      throw new Error("try to choose an unsatisfied version?");
     }
 
     // Great, move it from dependencies to choices.