added wrapper error that will provide file/line origin of an error

pkg.go

@@ -2,6 +2,8 @@ package x
 
 import (
 	"errors"
+	"fmt"
+	"runtime"
 )
 
 func Assert(cond bool, msg string) {
@@ -37,3 +39,39 @@ func (i *invariants) First() error {
 func (i *invariants) All() []error {
 	return i.errs
 }
+
+type xError struct {
+	LineNo int
+	File   string
+	E      error
+	Debug  bool
+}
+
+func (e *xError) Error() string {
+	if e.Debug {
+		return fmt.Sprintf(
+			"%s\n\t%s:%d", e.E, e.File, e.LineNo,
+		)
+	}
+	return e.E.Error()
+}
+
+func (e *xError) Unwrap() error {
+	return e.E
+}
+
+func NewError(unwrapped error, debug bool) error {
+	_, file, line, ok := runtime.Caller(1)
+
+	if !ok {
+		file = "unknown"
+		line = 0
+	}
+
+	return &xError{
+		LineNo: line,
+		File:   file,
+		E:      unwrapped,
+		Debug:  debug,
+	}
+}