Move "skip ci" logic into global pipeline conditions (#2216)

... and make custom errors follow std err conventions

this fix a 500 response if the whole pipeline is filtered out

server/pipeline/errors.go

@@ -22,6 +22,14 @@ func (e ErrNotFound) Error() string {
 	return e.Msg
 }
 
+func (e ErrNotFound) Is(target error) bool {
+	_, ok := target.(ErrNotFound) //nolint:errorlint
+	if !ok {
+		_, ok = target.(*ErrNotFound) //nolint:errorlint
+	}
+	return ok
+}
+
 type ErrBadRequest struct {
 	Msg string
 }
@@ -30,6 +38,14 @@ func (e ErrBadRequest) Error() string {
 	return e.Msg
 }
 
+func (e ErrBadRequest) Is(target error) bool {
+	_, ok := target.(ErrBadRequest) //nolint:errorlint
+	if !ok {
+		_, ok = target.(*ErrBadRequest) //nolint:errorlint
+	}
+	return ok
+}
+
 type ErrFiltered struct {
 	Msg string
 }
@@ -37,3 +53,11 @@ type ErrFiltered struct {
 func (e ErrFiltered) Error() string {
 	return "ignoring hook: " + e.Msg
 }
+
+func (e *ErrFiltered) Is(target error) bool {
+	_, ok := target.(ErrFiltered) //nolint:errorlint
+	if !ok {
+		_, ok = target.(*ErrFiltered) //nolint:errorlint
+	}
+	return ok
+}