fix undefined ctx in onPhaseBegin

Author: darthfiddler

src/core/flow.js

@@ -360,7 +360,7 @@ export function FlowWithPhases({
 
   // Helper to perform start-of-phase initialization.
   const startPhase = function(state, config) {
-    const G = config.onPhaseBegin(state.G, ctx);
+    const G = config.onPhaseBegin(state.G, state.ctx);
 
     const ctx = { ...state.ctx };
     ctx.playOrderPos = config.turnOrder.first(G, ctx);