Add error for when pushdata is exceptionally large

lib/script.js

@@ -267,6 +267,8 @@ Script.prototype.writeBuffer = function(buf) {
     opcodenum = Opcode.map.OP_PUSHDATA2;
   } else if (buf.length < Math.pow(2, 32)) {
     opcodenum = Opcode.map.OP_PUSHDATA4;
+  } else {
+    throw new Error("You can't push that much data");
   }
   this.chunks.push({
     buf: buf,