Remove indent when line is empty

src/main/java/uk/ac/rhul/cs/javatester/TesterOutput.java

@@ -43,11 +43,12 @@ public class TesterOutput {
 
         if (!isHTML) {
             // will work for \r\n and \n
-            indented = CODE_INDENT;
+            indented = "";
             if (code == null) {
-                indented += code;
-            } else {
-                indented += code.replaceAll("\n", "\n" + CODE_INDENT);
+                indented = CODE_INDENT + code;
+            } else if (code.length() > 0) {
+                indented
+                    = CODE_INDENT + code.replaceAll("\n", "\n" + CODE_INDENT);
             }
         }