Bunq-install should display error message and not installation util. (bunq/sdk_php#133)

[jorijn]

This PR closes/fixes the following issues:

• Closes bunq/sdk_php#133
  • [x] Tested

needs #138

[OGKevin]

@sandervdo as I've also committed in this PR, please 👀

[OGKevin]

@sandervdo pushed.

[OGKevin]

@andrederoos