Segmentation fault may occur if a repository is unavailable

[dacleyra]

Describe the bug

Segmentation fault may occur if a repository is unavailable

To Reproduce
Steps to reproduce the behavior:

Running an appsody init kabanero/java-spring-boot2, I get a segmentation fault

This seems to randomly happen if I have a repository that is unreachable

[Error] Does the APIVersion of your repository match what the Appsody CLI currently supports? (v2). The following indices could not be read. skipping:
- Repository: kab
  Reason: Could not download http://kabanero-index-kabanero.apps.my.cluster/kabanero-index.yaml: 503 Service Unavailable
- Repository: kabanero
  Reason: Get https://github.com/kabanero-io/kabanero-stack-hub/releases/download/0.9.0/kabanero-stack-hub-index.yaml: EOF

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x9b5b3b]

goroutine 1 [running]:
github.com/appsody/appsody/cmd.initAppsody(0x7ffdcb7766dd, 0x1a, 0x0, 0x0, 0xc0001ac390, 0x0, 0x0)
        /home/travis/gopath/src/github.com/appsody/appsody/cmd/init.go:169 +0xafb
github.com/appsody/appsody/cmd.newInitCmd.func1(0xc00018ec80, 0xc000198f30, 0x1, 0x1, 0x0, 0x0)
        /home/travis/gopath/src/github.com/appsody/appsody/cmd/init.go:85 +0xb9
github.com/appsody/appsody/vendor/github.com/spf13/cobra.(*Command).execute(0xc00018ec80, 0xc000198ee0, 0x1, 0x1, 0xc00018ec80, 0xc000198ee0)
        /home/travis/gopath/src/github.com/appsody/appsody/vendor/github.com/spf13/cobra/command.go:762 +0x465
github.com/appsody/appsody/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc00018ea00, 0x5, 0x0, 0xc62d00)
        /home/travis/gopath/src/github.com/appsody/appsody/vendor/github.com/spf13/cobra/command.go:852 +0x2ec
github.com/appsody/appsody/vendor/github.com/spf13/cobra.(*Command).Execute(...)
        /home/travis/gopath/src/github.com/appsody/appsody/vendor/github.com/spf13/cobra/command.go:800
github.com/appsody/appsody/cmd.ExecuteE(0xc4ffec, 0x5, 0xc4ffe4, 0x5, 0xc00002c004, 0x45, 0xc62d00, 0xc00000e018, 0xc62d00, 0xc00000e020, ...)
        /home/travis/gopath/src/github.com/appsody/appsody/cmd/root.go:240 +0x312
github.com/appsody/appsody/cmd.Execute(0xc4ffec, 0x5, 0xc4ffe4, 0x5)
        /home/travis/gopath/src/github.com/appsody/appsody/cmd/root.go:226 +0x1ab
main.main()
        /home/travis/gopath/src/github.com/appsody/appsody/main.go:27 +0x51
[dacleyra@greyjoy06 kabanero-io]$ appsody repo list

NAME            URL
*incubator      https://github.com/appsody/stacks/releases/latest/download/incubator-index.yaml
experimental    https://github.com/appsody/stacks/releases/latest/download/experimental-index.yaml
kab             http://kabanero-index-kabanero.apps.my.cluster/kabanero-index.yaml
kabanero        https://github.com/kabanero-io/kabanero-stack-hub/releases/download/0.9.0/kabanero-stack-hub-index.yaml


[dacleyra@greyjoy06 kabanero-io]$ appsody list
[Error] The following indices could not be read, skipping:
- Repository: kab
  Reason: Could not download http://kabanero-index-kabanero.apps.my.cluster/kabanero-index.yaml: 503 Service Unavailable


REPO            ID                              VERSION         TEMPLATES                       DESCRIPTION
experimental    go-modules                      0.1.0           *default                        Runtime for Go using Go 1.11+ modules for dependencies
experimental    java-spring-boot2-liberty       0.1.11          *default                        Spring Boot on Open Liberty & OpenJ9 using Maven
experimental    nodejs-functions                0.2.0           *simple                         Serverless runtime for Node.js functions
experimental    rocket                          0.1.0           *simple                         Rocket web framework for Rust
experimental    rust                            0.2.0           *simple                         Runtime for Rust applications
experimental    vertx                           0.1.4           *default                        Eclipse Vert.x runtime for running Java applications
*incubator      java-microprofile [Deprecated]  0.2.27          *default                        Eclipse MicroProfile on Open Liberty & OpenJ9 using Maven
*incubator      java-openliberty                0.2.12          *default, kafka                 Eclipse MicroProfile & Jakarta EE on Open Liberty & OpenJ9
                                                                                                using Maven
*incubator      java-spring-boot2               0.3.29          *default, kafka, kotlin         Spring Boot using OpenJ9 and Maven
*incubator      kitura                          0.2.6           *default                        Runtime for Kitura applications
*incubator      node-red                        0.1.3           *simple                         Node-RED runtime for running flows
*incubator      nodejs                          0.3.5           *simple                         Runtime for Node.js applications
*incubator      nodejs-express                  0.4.9           kafka, scaffold, *simple        Express web framework for Node.js
*incubator      nodejs-loopback                 0.3.0           *scaffold                       LoopBack 4 API Framework for Node.js
*incubator      python-flask                    0.2.3           *simple                         Flask web Framework for Python
*incubator      quarkus                         0.3.6           *default, kafka                 Quarkus runtime for running Java applications
*incubator      starter                         0.1.3           *simple                         Runnable starter stack, copy to create a new stack
*incubator      swift                           0.3.0           *simple                         Appsody runtime for Swift applications
kabanero        java-openliberty                0.2.12          *default, kafka                 Eclipse MicroProfile & Jakarta EE on Open Liberty & OpenJ9
                                                                                                using Maven
kabanero        java-spring-boot2               0.3.29          *default, kafka, kotlin         Spring Boot using OpenJ9 and Maven
kabanero        nodejs                          0.3.6           *simple                         Runtime for Node.js applications
kabanero        nodejs-express                  0.4.8           kafka, scaffold, *simple        Express web framework for Node.js
kabanero        quarkus                         0.3.6           *default, kafka                 Quarkus runtime for running Java applications

Expected behavior
success

Actual behaviour
segfault

Environment Details (please complete the following information):

• OS: rhel 7.3
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

If applicable please specify:

• CLI version: 0.6.1
• Stack you are using:

Screenshots
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Additional context
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