Nuke: proxy mode validator refactory to new publisher

openpype/hosts/nuke/plugins/publish/help/validate_proxy_mode.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<root>
+    <error id="main">
+        <title>Proxy mode</title>
+        <description>
+## Invalid proxy mode value
+
+Nuke is set to use Proxy. This is not supported by publisher.
+
+### How to repair?
+
+1. Use Repair button.
+2. Hit Reload button on the publisher.
+        </description>
+    </error>
+</root>

openpype/hosts/nuke/plugins/publish/validate_proxy_mode.py

@@ -1,5 +1,6 @@
 import pyblish
 import nuke
+from openpype.pipeline import PublishXmlValidationError
 
 
 class FixProxyMode(pyblish.api.Action):
@@ -7,7 +8,7 @@ class FixProxyMode(pyblish.api.Action):
     Togger off proxy switch OFF
     """
 
-    label = "Proxy toggle to OFF"
+    label = "Repair"
     icon = "wrench"
     on = "failed"
 
@@ -30,4 +31,7 @@ class ValidateProxyMode(pyblish.api.ContextPlugin):
         rootNode = nuke.root()
         isProxy = rootNode["proxy"].value()
 
-        assert not isProxy, "Proxy mode should be toggled OFF"
+        if not isProxy:
+            raise PublishXmlValidationError(
+                self, "Proxy mode should be toggled OFF"
+            )