Fix weird lint output

[n3tr]

fixes #1218

Since I can't reproduce it by myself, I use https://github.com/dtinth/pixelpaint to reproduce and verify.

Result

Compiled with warnings.

Warning in ./src/App.js

/Users/n3tr/Code/js/pixelpaint/src/App.js
  45:49  warning  Unexpected mix of '&&' and '||'  no-mixed-operators
  46:44  warning  Unexpected mix of '&&' and '||'  no-mixed-operators

✖ 2 problems (0 errors, 2 warnings)


Warning in ./src/ReduxCanvasV3.js

/Users/n3tr/Code/js/pixelpaint/src/ReduxCanvasV3.js
  25:5  warning  Expected a default case  default-case

✖ 1 problem (0 errors, 1 warning)


You may use special comments to disable some warnings.
Use // eslint-disable-next-line to ignore the next line.
Use /* eslint-disable */ to ignore all warnings in a file.

[gaearon]

This line would crash if lines had no elements.
I think it should be if (lines[0] && ...

[n3tr]

I don't think it would crash since lines come from message.split('\n'); and it should has at least one element of empty string.

We're also checking if (lines[0].lastIndexOf('!') !== -1) (line 38) and it would be false if lines[0] is an empty string.

[gaearon]

You're right.