API: The Error Interface

at\exceptable\Error

Interface for error cases for use by an Exceptable, or as a standalone error value.

Error::__invoke()
```
public __invoke( array $context = [], Throwable $previous = null ) : Exceptable
```
Factory method: proxies Error::newExceptable(). @see Error::newExceptable() @see https://php.net/__invoke
Error::code()
```
public code() : int
```
Gets the error code for this case.
- returns int: An error code
Error::exceptableType()
```
public exceptableType() : string
```
Gets the name of the proper Exceptable class to throw this Error as.
- returns string: A fully qualified Exceptable classname
Error::message()
```
public message( array $context ) : string
```
Gets the error message for this case, using the given context.
- parameters:
  - array $context: Contextual information, used for formatting.
- returns string: An error message
Error::newExceptable
```
public newExceptable( array $context = [], Throwable $previous = null ) : Exceptable
```
Factory: creates an Exceptable from this Error case.
- parameters:
  - array $context Contextual information, used both for formatting and to pass along to the Exceptable.
  - Throwable $previous: Previous exception, if any.
- returns Exceptable: A new Exceptable using this Error case