docs: public int getLineOffset(int line) {
          try {
              loadFileData();
          } catch (IOException e) {
              System.err.println("SourceFile.getLineOffset: " + e.getMessage());
              return -1;
          }
          if (line < 0 || line >= numLines) {
              return -1;
          }
          return lineNumberMap[line];
      }