fix: Prevent next forward calls when isGenerating=true (#371)

### Type of change

- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] Documentation update (improves or adds clarity to existing
documentation)

### Tested on

- [ ] iOS
- [ ] Android

Author: pweglik

src/controllers/LLMController.ts

@@ -145,7 +145,8 @@ export class LLMController {
   public delete() {
     if (this._isGenerating) {
       throw new Error(
-        'Model is generating! You cannot delete the model now. You need to interrupt first.'
+        getError(ETError.ModelGenerating) +
+          'You cannot delete the model now. You need to interrupt first.'
       );
     }
     this.onToken?.remove();
@@ -159,6 +160,9 @@ export class LLMController {
     if (!this._isReady) {
       throw new Error(getError(ETError.ModuleNotLoaded));
     }
+    if (this._isGenerating) {
+      throw new Error(getError(ETError.ModelGenerating));
+    }
     try {
       this.responseCallback('');
       this.isGeneratingCallback(true);