Don't fail writing text outside screen

- Adding np check not to try using item outside of a screen
- This fix essentially discards text write beyond screen bounds
- Fixes #993

spring-shell-core/src/main/java/org/springframework/shell/component/view/screen/DefaultScreen.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -300,12 +300,14 @@ public void text(String text, int x, int y) {
 			for (int i = 0; i < text.length() && i < columns; i++) {
 				char c = text.charAt(i);
 				DefaultScreenItem item = layer.getScreenItem(x + i, y);
-				item.content = Character.toString(c);
-				if (color > -1) {
-					item.foreground = color;
-				}
-				if (style > -1) {
-					item.style = style;
+				if (item != null) {
+					item.content = Character.toString(c);
+					if (color > -1) {
+						item.foreground = color;
+					}
+					if (style > -1) {
+						item.style = style;
+					}
 				}
 			}
 		}

spring-shell-core/src/test/java/org/springframework/shell/component/view/screen/ScreenTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,7 @@
 import org.springframework.shell.geom.VerticalAlign;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 class ScreenTests extends AbstractViewTests {
@@ -105,4 +106,22 @@ void writeTextFromWriterLayerOverrides() {
 		assertThat(items[0][3].getContent()).isEqualTo("t");
 	}
 
+	@Test
+	void discardAndDoNotErrorTextWriteOutsideScreen() {
+		assertThatCode(() -> {
+			screen24x80.writerBuilder().build().text("text", 79, 0);
+			screen24x80.writerBuilder().build().text("text", 80, 0);
+			screen24x80.writerBuilder().build().text("text", 0, 24);
+		}).doesNotThrowAnyException();
+	}
+
+	@Test
+	void discardAndDoNotErrorBorderWriteOutsideScreen() {
+		assertThatCode(() -> {
+			screen24x80.writerBuilder().build().border(0, 0, 81, 24);
+			screen24x80.writerBuilder().build().border(0, 0, 80, 25);
+			screen24x80.writerBuilder().build().border(0, 0, 81, 25);
+		}).doesNotThrowAnyException();
+	}
+
 }