monaco doesn't fail gracefully during maintenance windows

[zachBridges]

Describe the bug

When a Dynatrace tenant is in maintenance mode, the monaco CLI does not fail gracefully during a download operation.

How to reproduce

1. Dynatrace tenant is in maintenance
2. Perform monaco download

Additional context

• This would be a very nice enhancement; I assumed the error was PEBKAC until I saw the tenant was down. If this is not an issue the team wants to work on, feel free to close this issue.
• I encountered this issue using oh-my-zsh in iTerm2 on OSX
• The time at which the tenant was down was roughly 8:30PM EST.

Thanks!

Input/output:

➜  com-dynatrace-ace-monitoring-configuration git:(master) ✗ monaco download -e="./iam/environments-dev.yaml"
You are using the new CLI structure which is currently in Beta.

Please provide feedback here:
  https://github.com/dynatrace-oss/dynatrace-monitoring-as-code/issues/45.

We plan to make this CLI GA in version 2.0.0

2021-05-24 20:42:32 INFO  Dynatrace Monitoring as Code v1.5.3
2021-05-24 20:42:32 INFO  Creating base project name deve2e
2021-05-24 20:42:32 INFO   --- GETTING CONFIGS for calculated-metrics-log
2021-05-24 20:42:33 ERROR error getting client list from api calculated-metrics-log invalid character '<' looking for beginning of value
2021-05-24 20:42:33 ERROR error getting configs from API calculated-metrics-log %!v(MISSING)
2021-05-24 20:42:33 INFO   --- GETTING CONFIGS for notification
2021-05-24 20:42:33 ERROR error getting client list from api notification invalid character '<' looking for beginning of value
2021-05-24 20:42:33 ERROR error getting configs from API notification %!v(MISSING)
2021-05-24 20:42:33 INFO   --- GETTING CONFIGS for slo
2021-05-24 20:42:34 ERROR error getting client list from api slo invalid character '<' looking for beginning of value
2021-05-24 20:42:34 ERROR error getting configs from API slo %!v(MISSING)
2021-05-24 20:42:34 INFO   --- GETTING CONFIGS for custom-service-dotnet
2021-05-24 20:42:34 ERROR error getting client list from api custom-service-dotnet invalid character '<' looking for beginning of value
2021-05-24 20:42:34 ERROR error getting configs from API custom-service-dotnet %!v(MISSING)
2021-05-24 20:42:34 INFO   --- GETTING CONFIGS for application-mobile
2021-05-24 20:42:34 ERROR error getting client list from api application-mobile invalid character '<' looking for beginning of value
2021-05-24 20:42:34 ERROR error getting configs from API application-mobile %!v(MISSING)
2021-05-24 20:42:34 INFO   --- GETTING CONFIGS for anomaly-detection-metrics
2021-05-24 20:42:35 ERROR error getting client list from api anomaly-detection-metrics invalid character '<' looking for beginning of value
2021-05-24 20:42:35 ERROR error getting configs from API anomaly-detection-metrics %!v(MISSING)
2021-05-24 20:42:35 INFO   --- GETTING CONFIGS for alerting-profile
2021-05-24 20:42:35 ERROR error getting client list from api alerting-profile invalid character '<' looking for beginning of value
2021-05-24 20:42:35 ERROR error getting configs from API alerting-profile %!v(MISSING)
2021-05-24 20:42:35 INFO   --- GETTING CONFIGS for custom-service-nodejs
2021-05-24 20:42:35 ERROR error getting client list from api custom-service-nodejs invalid character '<' looking for beginning of value
2021-05-24 20:42:35 ERROR error getting configs from API custom-service-nodejs %!v(MISSING)
2021-05-24 20:42:35 INFO   --- GETTING CONFIGS for custom-service-php
2021-05-24 20:42:36 ERROR error getting client list from api custom-service-php invalid character '<' looking for beginning of value
2021-05-24 20:42:36 ERROR error getting configs from API custom-service-php %!v(MISSING)
2021-05-24 20:42:36 INFO   --- GETTING CONFIGS for request-naming-service
2021-05-24 20:42:36 ERROR error getting client list from api request-naming-service invalid character '<' looking for beginning of value
2021-05-24 20:42:36 ERROR error getting configs from API request-naming-service %!v(MISSING)
2021-05-24 20:42:36 INFO   --- GETTING CONFIGS for application-web
2021-05-24 20:42:36 ERROR error getting client list from api application-web invalid character '<' looking for beginning of value
2021-05-24 20:42:36 ERROR error getting configs from API application-web %!v(MISSING)
2021-05-24 20:42:36 INFO   --- GETTING CONFIGS for maintenance-window
2021-05-24 20:42:37 ERROR error getting client list from api maintenance-window invalid character '<' looking for beginning of value
2021-05-24 20:42:37 ERROR error getting configs from API maintenance-window %!v(MISSING)
2021-05-24 20:42:37 INFO   --- GETTING CONFIGS for dashboard
2021-05-24 20:42:37 ERROR error getting client list from api dashboard invalid character '<' looking for beginning of value
2021-05-24 20:42:37 ERROR error getting configs from API dashboard %!v(MISSING)
2021-05-24 20:42:37 INFO   --- GETTING CONFIGS for calculated-metrics-service
2021-05-24 20:42:37 ERROR error getting client list from api calculated-metrics-service invalid character '<' looking for beginning of value
2021-05-24 20:42:37 ERROR error getting configs from API calculated-metrics-service %!v(MISSING)
2021-05-24 20:42:37 INFO   --- GETTING CONFIGS for extension
^C 

^C is the interrupt, ctrl/cmd+C