Fix unhandled error when missing release args and fix use of uninitialized name value

Changes:

In both stage and release, ctx.name is used while it's still uninitialized causing null to be displayed as the app name (as described in #36). This fixes this by not using the context name and deriving the name directly.
When running pear release without a specified key, a Error: Cannot read properties of undefined (reading 'toString') error is thrown instead of cleanly showing the "A key or the channel name must be specified." error. This fixes that by skipping the parsing when the passed argument is null/undefined/empty.