fix: error cause param

[MeirionHughes]

Sorry, should have used these typings locally with levelup's typings.
Should be okay with a patch?

[ralphtheninja]

Should be okay with a patch?

Def. I have tested it locally and it works better, but now I get:

✓ ok
✓ Snapshots: test ReadStream implicit snapshot
# tests 1
# pass  1
✓ ok
# tests 121
# pass  121
✓ ok
not ok 242 assert out of order
not ok 243 assert out of order
not ok 244 unexpected additional plan
not ok 245 assert out of order
not ok 246 unexpected additional plan
not ok 247 assert out of order
not ok 248 unexpected additional plan
not ok 249 assert out of order
not ok 250 unexpected additional plan
not ok 251 assert out of order
not ok 252 unexpected additional plan
not ok 253 assert out of order
not ok 254 unexpected additional plan
not ok 255 assert out of order
not ok 256 unexpected additional plan
not ok 257 assert out of order
not ok 258 unexpected additional plan
not ok 259 assert out of order
not ok 260 unexpected additional plan
not ok 261 assert out of order
not ok 262 unexpected additional plan
not ok 263 assert out of order
not ok 264 unexpected additional plan
not ok 265 assert out of order
not ok 266 unexpected additional plan
not ok 267 assert out of order
not ok 268 unexpected additional plan
not ok 269 assert out of order
not ok 270 unexpected additional plan
not ok 271 assert out of order
not ok 272 unexpected additional plan
not ok 273 assert out of order
not ok 274 unexpected additional plan
not ok 275 unexpected additional plan

Maybe some tweak needed for levelup?

[MeirionHughes]

yeah I think that is due to my hack of the test runner - the typings themselves, and this pr, look okay.

[ralphtheninja]

1.1.1