Edited Issue: Error lines don't end in proper newline [729]

Type the following into the repl:

```
> a
ReferenceError: a is not defined
```

Now the cursor is on the third line after `>`. Type `a=123` and press enter:

```
> a
ReferenceError: a is not defined> a=123
123
> ```

The echo line is appended to the previous output.