purs docs --tags ctags fails occasionally

[yihuang]

Below is the error message when it happens, the file output/Data.String.CodeUnits/docs.json is empty. Work around is to delete the file and run it again.
It happens occasionally, I've tried to delete whole output directory, but it doesn't happen again.

$ spago docs -f ctags
Generating documentation for the project. This might take a while..
purs: An internal error occurred during compilation: Failed to decode: output/Data.String.CodeUnits/docs.jsonThe input could not be parsed as JSON
aeson said: Error in $: not enough input
Please report this at https://github.com/purescript/purescript/issues
CallStack (from HasCallStack):
  error, called at src/Language/PureScript/Crash.hs:24:3 in purescript-0.13.2-6QPLI9hJaMv7vmLTEn2Yqo:Language.PureScript.Crash
  internalError, called at src/Language/PureScript/Docs/Collect.hs:120:19 in purescript-0.13.2-6QPLI9hJaMv7vmLTEn2Yqo:Language.PureScript.Docs.Collect
spago: Docs generation failed.

[sjpgarcia]

I just ran spago docs -f ctags on the entire package set and was unable to reproduce this. This seems to have been fixed somewhere down the line over the past two years so I think it's fair to close this for now.