FlutterAnalyzeWithResult not returning results

When I use FlutterAnalyzeWithResult and there is issues returned by the `flutter analyze` the method fails and does not even return.

## Expected Behavior
The **FlutterAnalyzeWithResult** should return the collection of lines of the output from the `flutter analyze`

## Current Behavior
The **FlutterAnalyzeWithResult** throws an error and do not allow me to handle the output

## Possible Solution
Idk, but I may help, I don't know how the generic runner works

## Steps to Reproduce (for bugs)
1. Create a single task with `FlutterAnalyzeWithResult(new FlutterAnalyzeSettings());`
2. In the flutter project, create some class that is not used
3. Run the cake task

## Context
I would like to get the output from the flutter analyze and send to pull request

## Your Environment
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* Module version used: `#addin "Cake.Flutter&version=0.1.2"`
* Operating System and PowerShell version: Microsoft Windows 10 Pro - 10.0.19041 N/A 19041