Empty stderr throws and error and blocks linter's code-checking pipe

[ehteqx]

Description

The problem seems to affect the linter only when used with linter-clojure (or other JVM-based languages linters). When no error is detected by the linter (thus leading to an empty stderr), an "Unknown error. The process terminated with no output. Error code: 0" message is shown [1] in Developers Tools Console and from now on the linter stops working until an error in the code is detected [2], and stderr populated. If, afterwards, no error is present in the code and the linter is triggered, still the linter shows the last non-empty stderr content [3]. The linter's functionality is therefore disrupted.

Reproducibility: 100%

Steps to reproduce

After the linter is installed...

1. Open (or create new file, then save it) a .clj file with obviously bugless code in it, i.e.:

(+ 1 2 3)

2. Save it, so as to trigger the linting process. Case [1] ensues.
3. Add code with errors i.e.:

(+ 1 2 3)
xyz

4. Save it, so as to trigger the linting process. An error at line 2 is detected "Cannot resolve xyz", but the linter itself works properly (case [2]).
5. Remove the buggy line:

(+ 1 2 3)
xyz

6. Save it, so as to trigger the linting process. Still, an error at line 2 is detected "Cannot resolve xyz", the the linter itself works properly but there's not even a line 2 (case [3]).

Suggested fix

See pull #55

Versions

OS : Ubuntu 16.04, fully updated
Atom install method : Official DEB package from https://atom.io/
AtomLinter and linter-clojure install method : From inside Atom, Packages section
linter version : 2.2.0 (steelbrain)
linter-clojure version : 1.1.3

• Output of atom --version :

Atom    : 1.19.3
Electron: 1.6.9
Chrome  : 56.0.2924.87
Node    : 7.4.0

• Output of apm --version :

apm  1.18.4
npm  3.10.10
node 6.9.5 x64
python 2.7.13
git 2.14.1

[Arcanemagus]

Fixed by #55.