initialize libxml error capture when we start processing XML on each thread.

error.go

@@ -1,7 +1,6 @@
 package xmlsec
 
 import (
-	"C"
 	"fmt"
 	"runtime"
 	"strings"
@@ -9,6 +8,9 @@ import (
 	"github.com/crewjam/errset"
 )
 
+// void captureXmlErrors();
+import "C"
+
 var globalErrors = map[uintptr]errset.ErrSet{}
 
 type libraryError struct {
@@ -61,13 +63,14 @@ func onXmlError(msg *C.char) {
 func startProcessingXML() {
 	runtime.LockOSThread()
 	globalErrors[getThreadID()] = errset.ErrSet{}
+	C.captureXmlErrors()
 }
 
 // stopProcessingXML unlocks the goroutine-thread lock and deletes the current
 // error stack.
 func stopProcessingXML() {
-	runtime.UnlockOSThread()
 	delete(globalErrors, getThreadID())
+	runtime.UnlockOSThread()
 }
 
 // popError returns the global error for the current thread and resets it to

xmlsec.go

@@ -27,9 +27,6 @@ import "C"
 // }
 import "C"
 
-// void captureXmlErrors();
-import "C"
-
 func init() {
 	C.xmlInitParser()
 
@@ -42,8 +39,6 @@ func init() {
 	if rv := C.xmlSecCryptoInit(); rv < 0 {
 		panic("xmlsec crypto initialization failed.")
 	}
-
-	C.captureXmlErrors()
 }
 
 func newDoc(buf []byte, idattrs []XMLIDOption) (*C.xmlDoc, error) {