CLI does not respect shelljs errors

Shelljs module does not fail in case shelljs.config.fatal is not set to true. However setting it true leads to some unexpected issues - the shelljs silently exits the process when calling tns platform add android@1.3.0 for example. So consider respecting the errors of shelljs, but make sure all operations work.

[slavchev]

I think we should increase the priority of this issue as I was debugging entirely different problem only to find that there were silent/missing error handling.

[rosen-vladimirov]

@Plamen5kov I think in most of the cases we would like to stop the execution in case shelljs encounters an error. However (as far as I remember), setting shelljs.config.fatal breaks the process immediately, so we have no chance to catch this. My suggestion is:

1. Implement a wrapper for shelljs:

class Shelljs implements IShelljs {
...
}
$injector.register("shelljs", shelljs);

1. Add a method in the new class, that executes shelljs action, checks for error and throws it in case there’s any error:

import * as shelljs from "shelljs";

class Shelljs implements IShelljs {
    constructor(private $logger: ILogger) { }
    public executeAction(command: string, commandArgs: string[]): any {
        const result = shelljs[command].apply(null, commandArgs);
        const err = shelljs.error();
        if (err) {
            this.$logger.trace("Encountered shelljs.error: ", err);
            throw new Error(err);
        }

        return result;
   }
}
$injector.register("shelljs", Shelljs);

1. Use the method anywhere you need shelljs. In case on a specific place you do not want to fail, you can try-catch the code there and continue the execution. Another option is to pass additional flag to the executeAction method.

// This will fail in case error is encountered:
this.$shelljs.executeAction('cp', ["-r", "./my-dir", "./my-dir2"]);

// This will not fail in case error is encountered:
try {
    this.$shelljs.executeAction('cp', ["-r", "./my-dir", "./my-dir2"]);
} catch (err) {
    // do smth with the error
}