correccion de error en repl cuando se redefinia una variable

src/interpreter/runtimeModel.ts

@@ -488,13 +488,21 @@ export class Evaluation {
   }
 
   protected *execVariable(node: Variable): Execution<void> {
+    const variableFullName = targetName(node, node.name)
+
+    if(this.currentFrame.locals.get(variableFullName)){
+      throw new Error('Can\'t redefine a variable')
+    }
+
     const value = yield* this.exec(node.value)
 
     assertNotVoid(value, `Cannot assign to variable '${node.name}': ${getExpressionFor(node.value)} produces no value, cannot assign it to a variable`)
 
     yield node
 
-    this.currentFrame.set(targetName(node, node.name), value)
+    this.currentFrame.set(variableFullName, value)
+
+
   }
 
   protected *execAssignment(node: Assignment): Execution<void> {

test/interpreter.test.ts

@@ -506,6 +506,24 @@ describe('Wollok Interpreter', () => {
         )
       })
 
+      it('Can\'t redefine a variable', () => {
+        const replEnvironment = buildEnvironment([{
+          name: REPL, content: `
+            const variableName = 1
+          `,
+        }])
+        interpreter = new Interpreter(Evaluation.build(replEnvironment, WRENatives))
+        const { error } = interprete(interpreter, 'var variableName = 2')
+        assertBasicError(error)
+        expect(getStackTraceSanitized(error)).to.deep.equal(
+          [
+            'wollok.lang.EvaluationError: Error: Can\'t redefine a variable',
+
+          ]
+        )
+      })
+
+
       it('should wrap void validation errors for assignment to void value', () => {
         const replEnvironment = buildEnvironment([{
           name: REPL, content: `