Fix parsing nested exports case

[huozhi]

Should support nested export condition (import or require etc), then the value has both types and default, should get the path from nested condition

       exports: {
            '.': {
              'import': {
                'types': './dist/index.d.ts',
                'default': './dist/index.mjs'
              },
              'require': {
                'types': './dist/index.d.ts',
                'default': './dist/index.js'
              }
            }
          }