The dash toggles to the previous namespace, but kubens has not recorded one for this context yet - first switch, or the per-context cache was cleared. Switch namespaces once with kubens [name] (that records the previous one), and kubens - toggles from then on.

## The error
```text
No previous namespace found for current context
```

## What to do
1. Switch once to record a previous namespace:
```bash
kubens [first]
kubens [second]
```
   Expected: Each prints `Active namespace is "[name]".`.
2. Toggle:
```bash
kubens -
```
   Expected: Prints `Active namespace is "[first]".`.
3. If it still fails, the cache lives per context under ~/.kube/cache/kubens/ - check it exists and is writable.
   Expected: Cache file present after a successful switch.

## When this applies
- the exact No previous namespace found for current context message
- first use of kubens - on a context
- after clearing ~/.kube/cache/kubens

## When it does NOT apply
- no namespace exists with name (different error)
- the dash toggling to an unexpected namespace (stale cache - switch twice)

## Works with
kubens (ahmetb/kubectx)

### no previous context found (kubectx -)
The kubectx twin of this error. Same shape: switch once with an explicit name first.

## Why it happens
kubens saves the previous namespace per context in a cache file under your home on every switch. No recorded switch for this context means the toggle has nothing to return to.

## Edge cases
- Each context tracks its own previous namespace - toggling after a context switch uses that context's history.
- Read-only HOME (containers) breaks the cache; use explicit names there.

## Resolved from
gh:nao1215/atago (e2e kubens behavior spec) - https://github.com/nao1215/atago/blob/HEAD/doc/e2e/kubectx.md