Fix prestate tracer for simple transfers

eth/tracers/internal/tracers/prestate_tracer.js

@@ -47,6 +47,12 @@
 	// result is invoked when all the opcodes have been iterated over and returns
 	// the final result of the tracing.
 	result: function(ctx, db) {
+		if (this.prestate === null) {
+			this.prestate = {};
+			// If tx is transfer-only, the recipient account
+			// hasn't been populated.
+			this.lookupAccount(ctx.to, db);
+		}
 		// At this point, we need to deduct the 'value' from the
 		// outer transaction, and move it back to the origin
 		this.lookupAccount(ctx.from, db);
@@ -79,7 +85,7 @@
 		}
 		// Whenever new state is accessed, add it to the prestate
 		switch (log.op.toString()) {
-			case "EXTCODECOPY": case "EXTCODESIZE": case "BALANCE":
+			case "EXTCODECOPY": case "EXTCODESIZE": case "EXTCODEHASH": case "BALANCE":
 				this.lookupAccount(toAddress(log.stack.peek(0).toString(16)), db);
 				break;
 			case "CREATE":