Fix possible NPE in InteractiveShellRunner

Signed-off-by: David Pilar <david@czpilar.net>

Author: czpilar

spring-shell-core/src/main/java/org/springframework/shell/core/InteractiveShellRunner.java

@@ -74,13 +74,14 @@ public void run(String[] args) throws Exception {
 			String input;
 			try {
 				input = this.inputProvider.readInput();
-				if (input.isEmpty()) { // ignore empty lines
-					continue;
-				}
 				if (input == null || input.equalsIgnoreCase("quit") || input.equalsIgnoreCase("exit")) {
 					print("Exiting the shell");
 					break;
 				}
+				if (input.isEmpty()) {
+					// ignore empty lines
+					continue;
+				}
 			}
 			catch (Exception e) {
 				if (this.debugMode) {