fix(browserify/test): result output references in error handling

[legobeat]

Fixes regression in error-handling in browserify tests introduced in f4292a0 (#698) where a non-existent res is referred in error-handling.

Ideally cases like this would be caught by lint.

[boneskull]

IIRC, I disabled the no-undef rule for tests because we use a lot of undefined variables in tests.

/Users/boneskull/projects/lavamoat/lavamoat/packages/browserify/test/globalRef.spec.js
  62:9  error  'checkThis' is not defined    no-undef
  67:9  error  'checkSelf' is not defined    no-undef
  72:9  error  'checkWindow' is not defined  no-undef
  77:9  error  'checkGlobal' is not defined  no-undef

/Users/boneskull/projects/lavamoat/lavamoat/packages/browserify/test/globalWrites.spec.js
  16:7   error  'xyz' is not defined  no-undef
  20:24  error  'xyz' is not defined  no-undef

/Users/boneskull/projects/lavamoat/lavamoat/packages/browserify/test/util.js
  42:17  error  'res' is not defined  no-undef
  45:12  error  'res' is not defined  no-undef
  46:15  error  'res' is not defined  no-undef

/Users/boneskull/projects/lavamoat/lavamoat/packages/core/test/globals.spec.js
   96:26  error  'xyz' is not defined     no-undef
  157:16  error  'abc' is not defined     no-undef
  158:22  error  'abc' is not defined     no-undef
  159:17  error  'abc' is not defined     no-undef
  160:15  error  'abc' is not defined     no-undef
  398:20  error  'chrome' is not defined  no-undef

/Users/boneskull/projects/lavamoat/lavamoat/packages/lavapack/test/sourcemaps.spec.js
  16:18  error  'UglifyJS' is not defined           no-undef
  55:30  error  'SourceMapConsumer' is not defined  no-undef

/Users/boneskull/projects/lavamoat/lavamoat/packages/tofu/test/inspectGlobals.spec.js
   17:15  error  'xyz' is not defined       no-undef
   22:7   error  'abc' is not defined       no-undef
   54:15  error  'zzz' is not defined       no-undef
   67:15  error  'a' is not defined         no-undef
   67:21  error  'b' is not defined         no-undef
   67:27  error  'c' is not defined         no-undef
   80:5   error  'xyz' is not defined       no-undef
   91:5   error  'z' is not defined         no-undef
   91:9   error  'xyz' is not defined       no-undef
   92:5   error  'xyz' is not defined       no-undef
   94:8   error  'abc' is not defined       no-undef
  109:5   error  'zzz' is not defined       no-undef
  122:15  error  'zzz' is not defined       no-undef
  133:5   error  'zzz' is not defined       no-undef
  133:15  error  'xyz' is not defined       no-undef
  160:5   error  'abc' is not defined       no-undef
  174:5   error  'abc' is not defined       no-undef
  409:9   error  'manifest' is not defined  no-undef
  423:5   error  'manifest' is not defined  no-undef

We should re-enable the rule and then disable it on a file-by-file basis.