Do not throw NPE if conversion messages is null (#12962)

Change-Id: Ie2b95ed4da89e2c5ab8b462300a6f4bd28dc7570

2 files changed, 24 insertions, 8 deletions

diff --git a/server/src/com/vaadin/ui/AbstractField.java b/server/src/com/vaadin/ui/AbstractField.java
index 6a52d6b849..b96e331889 100644
--- a/server/src/com/vaadin/ui/AbstractField.java
+++ b/server/src/com/vaadin/ui/AbstractField.java
@@ -783,15 +783,16 @@ public abstract class AbstractField<T> extends AbstractComponent implements
             ConversionException e) {
         String conversionError = getConversionError();
 
-        if (dataSourceType != null) {
-            conversionError = conversionError.replace("{0}",
-                    dataSourceType.getSimpleName());
-        }
-        if (e != null) {
-            conversionError = conversionError.replace("{1}",
-                    e.getLocalizedMessage());
+        if (conversionError != null) {
+            if (dataSourceType != null) {
+                conversionError = conversionError.replace("{0}",
+                        dataSourceType.getSimpleName());
+            }
+            if (e != null) {
+                conversionError = conversionError.replace("{1}",
+                        e.getLocalizedMessage());
+            }
         }
-
         return conversionError;
     }
 
diff --git a/server/tests/src/com/vaadin/tests/server/component/abstractfield/AbsFieldValueConversionError.java b/server/tests/src/com/vaadin/tests/server/component/abstractfield/AbsFieldValueConversionError.java
index ad762f8931..887f1b8ff3 100644
--- a/server/tests/src/com/vaadin/tests/server/component/abstractfield/AbsFieldValueConversionError.java
+++ b/server/tests/src/com/vaadin/tests/server/component/abstractfield/AbsFieldValueConversionError.java
@@ -54,6 +54,21 @@ public class AbsFieldValueConversionError extends TestCase {
 
     }
 
+    public void testNullConversionMessages() {
+        TextField tf = new TextField();
+        tf.setConverter(new StringToIntegerConverter());
+        tf.setPropertyDataSource(new MethodProperty<String>(paulaBean, "age"));
+        tf.setConversionError(null);
+        tf.setValue("abc");
+        try {
+            tf.validate();
+            fail();
+        } catch (InvalidValueException e) {
+            Assert.assertEquals(null, e.getMessage());
+        }
+
+    }
+
     public void testDefaultConversionErrorMessage() {
         TextField tf = new TextField();
         tf.setConverter(new StringToIntegerConverter());