wasm: fix compiler to be backwards compatible with old prop name

Author: pdubroy

packages/wasm/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@ohm-js/wasm",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "description": "Compile Ohm.js grammars to WebAsssembly",
   "main": "dist/index.js",
   "bin": {

packages/wasm/src/Compiler.js

@@ -918,7 +918,9 @@ export class Compiler {
         case pexprs.Terminal:
           return ir.terminal(exp.obj);
         case pexprs.UnicodeChar:
-          return ir.unicodeChar(exp.categoryOrProp);
+          // Support older versions of ohm-js (<= 17.2.1).
+          // TODO: Remove this eventually.
+          return ir.unicodeChar(exp.categoryOrProp ?? exp['category']);
         default:
           throw new Error(`not handled: ${exp.constructor.name}`);
       }