#52 fix NPE

Author: Alexey Belostotskiy

pom.xml

@@ -4,7 +4,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>ru.mail.jira.plugins</groupId>
     <artifactId>groovy</artifactId>
-    <version>1.20.0-jira8</version>
+    <version>1.20.1-jira8</version>
     <organization>
         <name>AtlasTeam</name>
         <url>https://atlasteam.ru/</url>

src/main/java/ru/mail/jira/plugins/groovy/impl/cf/FieldValueExtractor.java

@@ -201,7 +201,7 @@ private <T> T doExtractValue(
             result = ((Number) result).doubleValue();
         }
 
-        if (!tType.isInstance(result)) {
+        if (result != null && !tType.isInstance(result)) {
             logger.error("Result type ({}) doesn't match field type {}", result.getClass(), tType);
         }
         //todo: try to check collections in future if multi

src/test/java/it/ru/mail/jira/plugins/groovy/ScriptFieldIT.java

@@ -25,8 +25,7 @@
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.*;
 
 @RunWith(Arquillian.class)
 public class ScriptFieldIT {
@@ -107,6 +106,29 @@ public void scriptedFieldShouldWork() throws Exception {
         );
     }
 
+    @Test
+    public void nullValuesFieldShouldWork() throws Exception {
+        this.field = fieldHelper.createNumberField();
+        this.issue = issueHelper.createIssue(userHelper.getAdmin(), project);
+
+        FieldConfig fieldConfig = fieldHelper.getFirstConfig(field);
+
+        assertNotNull(fieldConfig);
+
+        String script = "return null";
+
+        FieldConfigForm form = new FieldConfigForm();
+        form.setCacheable(true);
+        form.setScriptBody(script);
+        form.setVelocityParamsEnabled(false);
+
+        fieldConfigRepository.updateConfig(userHelper.getAdmin(), fieldConfig.getId(), form);
+
+        MutableIssue issue = issueManager.getIssueObject(this.issue.getId());
+
+        assertNull(issue.getCustomFieldValue(field));
+    }
+
     private boolean isIssueReIndexed(ApplicationUser expectedAssignee) throws Exception {
         return issueHelper.search(
             userHelper.getAdmin(),