Add more explicit error logging when fetching detail. (#5895)

Signed-off-by: Michael Nelson <[email protected]>

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### Description of the change

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A user is getting an error in the UX showing "Unable to retrieve chart:
sql: no rows in result set" but no corresponding error in the backend.
Checking, I found that we don't actually log the error, other than the
request log showing the internal error without details:

```
I0119 19:05:27.529184       1 server.go:314] Requesting chart 'repo/kubeapps%2Fnginx' (latest version) in ns 'default'
I0119 19:05:27.530935       1 server.go:375] Requesting chart 'repo/kubeapps%2Fnginx' (latest version) in ns 'default'
I0119 19:05:27.535286       1 server.go:62] Internal 88.857512ms /kubeappsapis.core.packages.v1alpha1.PackagesService/GetAvailablePackageDetail
I0119 19:05:27.536622       1 server.go:62] Internal 90.361477ms /kubeappsapis.core.packages.v1alpha1.PackagesService/GetAvailablePackageVersions

```
With this change we'll have details about the actual error in the
backend logs.

### Benefits

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### Possible drawbacks

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### Applicable issues

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- fixes #

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Signed-off-by: Michael Nelson <[email protected]>

Author: absoludity

cmd/kubeapps-apis/plugins/helm/packages/v1alpha1/server.go

@@ -318,6 +318,7 @@ func (s *Server) GetAvailablePackageDetail(ctx context.Context, request *corev1.
 		chart, err = s.manager.GetChartVersion(namespace, unescapedChartID, version)
 	}
 	if err != nil {
+		log.Errorf("Failed to request chart '%s' in ns '%s': %v", unescapedChartID, namespace, err)
 		return nil, status.Errorf(codes.Internal, "Unable to retrieve chart: %v", err)
 	}