Tweaked C++ worker program to be more robust to bad inputs.

cpp/QrCodeGeneratorWorker.cpp

@@ -37,7 +37,7 @@ using qrcodegen::QrCode;
 using qrcodegen::QrSegment;
 
 
-static const QrCode::Ecc ECC_LEVELS[] = {
+static const std::vector<QrCode::Ecc> ECC_LEVELS{
 	QrCode::Ecc::LOW,
 	QrCode::Ecc::MEDIUM,
 	QrCode::Ecc::QUARTILE,
@@ -83,7 +83,7 @@ int main() {
 		
 		try {  // Try to make QR Code symbol
 			const QrCode qr = QrCode::encodeSegments(segs,
-				ECC_LEVELS[errCorLvl], minVersion, maxVersion, mask, boostEcl == 1);
+				ECC_LEVELS.at(errCorLvl), minVersion, maxVersion, mask, boostEcl == 1);
 			// Print grid of modules
 			std::cout << qr.getVersion() << std::endl;
 			for (int y = 0; y < qr.getSize(); y++) {