`cacheExtraArgs` suggests string but is initialized as map `cannot overwrite table with non table for SNIP.cacheExtraArgs (map[]))`

Describe the bug
The default values suggest to define a string for cacheExtraArgs - but due to the initialization as map Helm complains about a type mismatch:

cannot overwrite table with non table for {{SNIP}}.kube-httpcache.cacheExtraArgs (map[]))

ref: https://github.com/mittwald/kube-httpcache/blob/v0.7.0/chart/values.yaml#L50-L53

To Reproduce

• add kube-httpcache as dependency of another helm chart
• override the values / essentially comment in the sample values:

kube-httpcache:
  cacheExtraArgs: |
    - -v=8
    - -varnish-additional-parameters=vcc_allow_inline_c=on

https://github.com/mittwald/kube-httpcache/blob/v0.7.0/chart/values.yaml#L50-L53

Expected behavior

The chart should apply the extra args

Actual behavior

Applying the chart causes Helm to complain with a message like this:

coalesce.go:220: warning: cannot overwrite table with non table for {{SNIP}}.kube-httpcache.cacheExtraArgs (map[])

Environment:

• Kubernetes version: 1.24.6
• kube-httpcache version: v0.7.0

Start with chart/values.yaml around lines 50–53 and compare the declared default for cacheExtraArgs with the documented override. Reproduce the issue by using kube-httpcache as a Helm dependency and applying the sample values; done means Helm accepts the override and the chart applies the extra arguments without the type-mismatch warning.