Modify the error message of CLI app.

src/main/java/azgracompress/DataCompressor.java

@@ -12,6 +12,7 @@ import azgracompress.fileformat.FileExtensions;
 import org.apache.commons.cli.*;
 
 import java.io.IOException;
+import java.util.Optional;
 
 public class DataCompressor {
     public static void main(String[] args) {
@@ -27,8 +28,12 @@ public class DataCompressor {
                 formatter.printHelp(CliConstants.MAIN_HELP, options);
                 return;
             }
+            if (e.getMessage().startsWith("Missing required option:")) {
                 System.err.println("Error: Missing required option, see usage below. :^)");
                 formatter.printHelp(CliConstants.MAIN_HELP, options);
+            } else {
+                System.err.println("Error: " + e.getMessage());
+            }
             return;
         }
 

src/main/java/azgracompress/cli/ParseResult.java

-package azgracompress.cli;
-
-public class ParseResult<T> {
-    private final boolean success;
-    private final T value;
-    private final String errorMessage;
-
-    public ParseResult(final String errorMessage) {
-        this.success = false;
-        this.value = null;
-        this.errorMessage = errorMessage;
-    }
-
-    public ParseResult(T value) {
-        this.success = true;
-        this.value = value;
-        this.errorMessage = null;
-    }
-
-    public boolean isSuccess() {
-        return success;
-    }
-
-    public T getValue() {
-        return value;
-    }
-
-    public String getErrorMessage() {
-        return errorMessage;
-    }
-}