export class InvalidProviderProvidedError extends Error { constructor ( provider ) { super ( `${ JSON . stringify ( provider ) } - is not a valid provider.` ) ; } } export class ClassNotInjectableError extends Error { constructor ( constructorName ) { super ( `Class ${ constructorName } is not injectable. Check if it's decorated with @Injectable() decorator` ) ; } } export class NoProviderError extends Error { constructor ( token , traceMessage ) { super ( `No provider for ${ token }. ${ traceMessage }` ) ; } }