perf: remove handler check

We'll just crash hard if there is an internal error.

lib/saxes.js

@@ -433,11 +433,7 @@ class SaxesParser {
       i: 0,
     };
     while (chunkState.i < limit) {
-      const handler = this[this.state];
-      if (!handler) {
-        throw new Error(this, `Unknown state: ${this.state}`);
-      }
-      handler.call(this, chunkState);
+      this[this.state].call(this, chunkState);
     }
 
     return this;