Merge branch 'type_has_trait'

Author: funny-falcon

error.go

@@ -94,8 +94,7 @@ func (e *Error) HasTrait(key Trait) bool {
 	cause := e
 	for cause != nil {
 		if !cause.transparent {
-			_, ok := cause.errorType.traits[key]
-			return ok
+			return cause.errorType.HasTrait(key)
 		}
 
 		cause = Cast(cause.Cause())

type.go

@@ -88,6 +88,12 @@ func (t *Type) IsOfType(other *Type) bool {
 	return false
 }
 
+// HasTrait checks if a type possesses the expected trait.
+func (t *Type) HasTrait(key Trait) bool {
+	_, ok := t.traits[key]
+	return ok
+}
+
 // IsOfType is a type check for errors.
 // Returns true either if both are of exactly the same type, or if the same is true for one of current type's ancestors.
 // For an error that does not have an errorx type, returns false.