add some changes

src/main/java/de/monticore/lang/monticar/generator/cpp/commands/LargestContourCommand.java

@@ -84,8 +84,9 @@ public class LargestContourCommand extends MathCommand {
         return new Instruction() {
             @Override
             public String getTargetLanguageInstruction() {
-                return  "double maxArea = 0;\n" +
-                        "int maxAreaContourId = -1;\n" +
+                return  "    std::vector<cv::Point> singleContour;\n" +
+                        "    double maxArea = 0;\n" +
+                        "    int maxAreaContourId = 0;\n" +
                         "   for (int j = 0; j < contours.size(); j++) {\n" +
                         "       double newArea = cv::contourArea(contours.at(j));\n" +
                         "       if (newArea > maxArea) {\n" +
@@ -93,7 +94,7 @@ public class LargestContourCommand extends MathCommand {
                         "           maxAreaContourId = j;\n" +
                         "       }\n" +
                         "   }\n" +
-                        "   return contours.at(maxAreaContourId);\n";
+                        "   return contours.empty()? singleContour: contours.at(maxAreaContourId);\n";
             }
 
             @Override

src/test/resources/results/armadillo/testMath/l0/test_math_largestContourCommandTest.h

@@ -16,8 +16,9 @@ void init()
 }
 std::vector<cv::Point> largestContour(const std::vector<std::vector<cv::Point>>& contours)
 {
-double maxArea = 0;
-int maxAreaContourId = -1;
+    std::vector<cv::Point> singleContour;
+    double maxArea = 0;
+    int maxAreaContourId = 0;
    for (int j = 0; j < contours.size(); j++) {
        double newArea = cv::contourArea(contours.at(j));
        if (newArea > maxArea) {
@@ -25,7 +26,7 @@ int maxAreaContourId = -1;
            maxAreaContourId = j;
        }
    }
-   return contours.at(maxAreaContourId);
+   return contours.empty()? singleContour: contours.at(maxAreaContourId);
 }
 void execute()
 {