Stop modifying the event data in onSerialReceive

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@adafruit/circuitpython-repl-js",
-  "version": "1.0.0",
+  "version": "1.2.3",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@adafruit/circuitpython-repl-js",
-      "version": "1.0.0",
+      "version": "1.2.3",
       "license": "MIT",
       "devDependencies": {}
     }

package.json

@@ -3,7 +3,7 @@
   "publishConfig": {
     "registry": "https://npm.pkg.github.com"
   },
-  "version": "1.0.0",
+  "version": "1.2.3",
   "description": "A JavaScript Module to help with interfacing to the REPL on CircuitPython Devices over serial",
   "main": "repl.js",
   "dependencies": {

repl.js

@@ -83,7 +83,7 @@ export class REPL {
                 }, this.promptTimeout
             );
         } catch (error) {
-            console.log("Awaiting prompt timed out.");
+            console.error("Awaiting prompt timed out.");
             return false;
         }
         return true;
@@ -102,15 +102,17 @@ export class REPL {
     }
 
     async onSerialReceive(e) {
-        // Prepend a partial token if it exists
+        // We don't want to modify e.data, so we make a copy of it
+        let data = e.data;
 
+        // Prepend a partial token if it exists
         if (this._partialToken) {
-            e.data = this._partialToken + e.data;
+            data = this._partialToken + data;
             this._partialToken = null;
         }
 
         // Tokenize the larger string and send to the parent
-        let tokens = this._tokenize(e.data);
+        let tokens = this._tokenize(data);
 
         // Remove any partial tokens and store for the next serial data receive
         if (tokens.length && this._hasPartialToken(tokens.slice(-1))) {