Fix the source directory was not attached when the protoc error message was not empty (#15553)

* Fix the source directory was not attached when the protoc error message was not empty

---------

Co-authored-by: zrlw <zrlw@sina.com>

Author: oxsean

dubbo-maven-plugin/src/main/java/org/apache/dubbo/maven/plugin/protoc/DubboProtocCompilerMojo.java

@@ -173,9 +173,8 @@ public void execute() throws MojoExecutionException, MojoFailureException {
                     "protoc did not exit cleanly. Review output for more information.");
             } else if (StringUtils.isNotBlank(getError())) {
                 getLog().warn("PROTOC: " + getError());
-            } else {
-                linkProtoFilesToMaven();
             }
+            linkProtoFilesToMaven();
         } catch (CommandLineException e) {
             throw new MojoExecutionException(e);
         }