fix: lsp error not showing correct error level #1631 (#1671)

fixes #1631 

ensures error level is preserved in the round trip to protobuf
conversion and back

backend/schema/errors.go

@@ -28,6 +28,7 @@ func (e Error) ToProto() *schemapb.Error {
 		Msg:       e.Msg,
 		Pos:       posToProto(e.Pos),
 		EndColumn: int64(e.EndColumn),
+		Level:     levelToProto(e.Level),
 	}
 }
 
@@ -38,6 +39,7 @@ func errorFromProto(e *schemapb.Error) *Error {
 		Pos:       posFromProto(e.Pos),
 		Msg:       e.Msg,
 		EndColumn: int(e.EndColumn),
+		Level:     levelFromProto(e.Level),
 	}
 }
 
@@ -111,8 +113,7 @@ func Wrapf(pos Position, endColumn int, err error, format string, args ...any) *
 		newEndColumn = endColumn
 		args = append(args, err)
 	}
-	e := Error{Msg: fmt.Sprintf(format, args...), Pos: newPos, EndColumn: newEndColumn}
-	return &e
+	return makeError(ERROR, newPos, newEndColumn, format, args...)
 }
 
 func SortErrorsByPosition(merr []*Error) {

backend/schema/protobuf_dec.go

@@ -17,6 +17,18 @@ func posFromProto(pos *schemapb.Position) Position {
 	}
 }
 
+func levelFromProto(level schemapb.Error_ErrorLevel) ErrorLevel {
+	switch level {
+	case schemapb.Error_INFO:
+		return INFO
+	case schemapb.Error_WARN:
+		return WARN
+	case schemapb.Error_ERROR:
+		return ERROR
+	}
+	panic(fmt.Sprintf("unhandled ErrorLevel %v", level))
+}
+
 func declListToSchema(s []*schemapb.Decl) []Decl {
 	var out []Decl
 	for _, n := range s {

backend/schema/protobuf_enc.go

@@ -9,6 +9,18 @@ import (
 	schemapb "github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/schema"
 )
 
+func levelToProto(level ErrorLevel) schemapb.Error_ErrorLevel {
+	switch level {
+	case INFO:
+		return schemapb.Error_INFO
+	case WARN:
+		return schemapb.Error_WARN
+	case ERROR:
+		return schemapb.Error_ERROR
+	}
+	panic(fmt.Sprintf("unhandled ErrorLevel %v", level))
+}
+
 func posToProto(pos Position) *schemapb.Position {
 	return &schemapb.Position{Line: int64(pos.Line), Column: int64(pos.Column), Filename: pos.Filename}
 }

buildengine/build_test.go

@@ -127,7 +127,7 @@ func assertBuildProtoErrors(msgs ...string) assertion {
 
 		expected := make([]*schema.Error, 0, len(msgs))
 		for _, msg := range msgs {
-			expected = append(expected, &schema.Error{Msg: msg})
+			expected = append(expected, &schema.Error{Msg: msg, Level: schema.ERROR})
 		}
 
 		// normalize results