Fixed typo in error message (#592).

src.ts/utils/hdnode.ts

@@ -206,7 +206,7 @@ export class HDNode {
                 if (index >= HardenedBit) { throw new Error('invalid path index - ' + component); }
                 result = result._derive(index);
             } else {
-                throw new Error('invlaid path component - ' + component);
+                throw new Error('invalid path component - ' + component);
             }
         }