Improve error handling for misconfigured hcatPath

- Add directory existence check in ensure_binary() before attempting make
- Provide clear error message when build directory doesn't exist
- Add troubleshooting section to README.md explaining common hcatPath mistakes
- Add tests for invalid hcatPath scenario and installed tool execution
- Helps users distinguish between hashcat path and hate_crack path

Fixes issue where users set hcatPath to hashcat installation directory
instead of hate_crack repository directory, causing confusing errors.

tests/test_invalid_hcatpath.py

@@ -0,0 +1,40 @@
+"""
+Test error handling when hcatPath is misconfigured.
+"""
+import os
+import sys
+import tempfile
+import json
+
+
+def test_ensure_binary_error_message(monkeypatch, capsys):
+    """Test that ensure_binary provides helpful error when build_dir doesn't exist."""
+    # Import the function
+    from hate_crack.main import ensure_binary
+    
+    # Test with non-existent build directory
+    fake_binary = "/nonexistent/path/to/binary"
+    fake_build_dir = "/opt/hashcat/hashcat-utils"  # Simulate user's error
+    
+    # Expect SystemExit when binary and build dir don't exist
+    try:
+        ensure_binary(fake_binary, build_dir=fake_build_dir, name="expander")
+        assert False, "Should have exited with error"
+    except SystemExit as e:
+        assert e.code == 1
+    
+    # Check that the error message mentions the build directory issue
+    captured = capsys.readouterr()
+    assert "Build directory" in captured.out or "does not exist" in captured.out
+    assert "hcatPath" in captured.out  # Should mention config issue
+    assert "hashcat-utils" in captured.out or "princeprocessor" in captured.out
+
+
+def test_ensure_binary_with_existing_binary():
+    """Test that ensure_binary succeeds when binary exists."""
+    from hate_crack.main import ensure_binary
+    
+    # Use a system binary that definitely exists
+    python_path = sys.executable
+    result = ensure_binary(python_path)
+    assert result == python_path