I believe the app should ignore invalid yaml files at all or has an option kinda "fail if yaml is invalid"

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Sonarqube has semver meta info:
https://github.com/SonarSource/helm-chart-sonarqube/releases/tag/sonarqube-4.0.0-sonarqube-dce-3.0.0
sonarqube-4.0.0+315.tgz

It seems the app expecting <chartname>-<version>.tgz file.

How to reproduce:

1. Create app:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: sonarqube
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://sonarsource.github.io/helm-chart-sonarqube
    chart: sonarqube
    targetRevision: 3.0.0
    helm:
      values: |
        fullnameOverride: sonarqube-test

  destination:
    name: in-cluster
    namespace: sonarqube

2. Apply and push
3. Bump targetRevision to 4.0.0
4. argo-compare branch main

Expected result:
Diff is shown

Actual result:

===> Running argo-compare version [v0.0.5]
===> Found the following changed Application files
- sonarqube/sonarqube.yaml
===> Processing changed application: [sonarqube/sonarqube.yaml]
tar: Error opening archive: Failed to open '/Users/user/.cache/argo-compare/https://sonarsource.github.io/helm-chart-sonarqube/sonarqube-4.0.0.tgz'
2023/01/09 14:50:59 exit status 1

It became too hard to test all possible options manually. Before moving forward with features, reaching at least ~70% in test coverage would be beneficial.

It might be worth getting rid of internal diff printing implementation in favor of generating unified diff and passing it to some external diffing tool.

It might be worth adding an optional flag enabling resulting manifest validation, for example, using kubeconform.

For example https://github.com/so-fancy/diff-so-fancy
It support unified diff output