fix TypedExprTools handling of TIf

std/haxe/macro/TypedExprTools.hx

@@ -62,7 +62,7 @@ class TypedExprTools {
 			case TCall(e1, el): with(e, TCall(f(e1), el.map(f)));
 			case TVar(v,eo): with(e, TVar(v, eo == null ? null : f(eo)));
 			case TFunction(fu): with(e, TFunction({ t: fu.t, args: fu.args, expr: f(fu.expr)}));
-			case TIf(e1, e2, e3): with(e, TIf(f(e1), f(e2), f(e3)));
+			case TIf(e1, e2, e3): with(e, TIf(f(e1), f(e2), e3 == null ? null : f(e3)));
 			case TSwitch(e1, cases, e2): with(e, TSwitch(e1, cases.map(function(c) return { values: c.values, expr: f(c.expr) }), e2 == null ? null : f(e2)));
 			case TPatMatch: throw false;
 			case TTry(e1, catches): with(e, TTry(f(e1), catches.map(function(c) return { v:c.v, expr: f(c.expr) })));
@@ -101,7 +101,7 @@ class TypedExprTools {
 			case TCall(e1, el): with(e, TCall(f(e1), el.map(f)), ft(e.t));
 			case TVar(v,eo): with(e, TVar(fv(v), eo == null ? null : f(eo)), ft(e.t));
 			case TFunction(fu): with(e, TFunction({ t: ft(fu.t), args: fu.args.map(function(arg) return { v: fv(arg.v), value: arg.value }), expr: f(fu.expr)}), ft(e.t));
-			case TIf(e1, e2, e3): with(e, TIf(f(e1), f(e2), f(e3)), ft(e.t));
+			case TIf(e1, e2, e3): with(e, TIf(f(e1), f(e2), e3 == null ? null : f(e3)), ft(e.t));
 			case TSwitch(e1, cases, e2): with(e, TSwitch(e1, cases.map(function(c) return { values: c.values, expr: f(c.expr) }), e2 == null ? null : f(e2)), ft(e.t));
 			case TPatMatch: throw false;
 			case TTry(e1, catches): with(e, TTry(f(e1), catches.map(function(c) return { v:fv(c.v), expr: f(c.expr) })), ft(e.t));