extractBasePath(expression) {
      const matches2 = expression.match(/[a-zA-Z_][a-zA-Z0-9_]*/g);
      return matches2 ? matches2[0] : "";
    }
Extracts the base path from an expression using regex pattern matching.
- Matches valid JavaScript variable names
- Returns the first match or empty string
- Valid names start with letter/underscore followed by alphanumeric/underscore

@param {string} expression - Expression to analyze
@returns {string} First valid variable name or empty string
@private