correct couple of bugs

Author: carlosuc3m

Diff for: src/main/java/io/bioimage/modelrunner/tensorflow/v2/api020/Tensorflow2Interface.java

@@ -198,7 +198,7 @@ public void loadModel(String modelFolder, String modelSource)
 				"serving_default");
 		}
 		catch (InvalidProtocolBufferException e) {
-			System.out.println("Invalid graph");
+			throw new LoadModelException(Types.stackTrace(e));
 		}
 	}