pcottle/learnGitBranching · info · CommandResult

<dynamic branch listing>

Error message

<dynamic branch listing>

What it means

Not a failure: printBranches formats the branch listing (selected branch prefixed with '* ', display names unquoted via split('"')[1]) and delivers it by throwing a CommandResult, the app's control-flow mechanism for command output.

Source

Thrown at src/js/git/index.js:853

};

GitEngine.prototype.printBranchesWithout = function(without) {
  var commitToBranches = this.getUpstreamBranchSet();
  var commitID = this.getCommitFromRef(without).get('id');

  var toPrint = commitToBranches[commitID].map(function (branchJSON) {
    branchJSON.selected = this.HEAD.get('target').get('id') == branchJSON.id;
    return branchJSON;
  }, this);
  this.printBranches(toPrint);
};

GitEngine.prototype.printBranches = function(branches) {
  var result = '';
  branches.forEach(branch => {
    result += (branch.selected ? '* ' : '') + this.resolveName(branch.id).split('"')[1] + '\n';
  });
  throw new CommandResult({
    msg: result
  });
};

GitEngine.prototype.printTags = function(tags) {
  var result = '';
  tags.forEach(function (tag) {
    result += tag.id + '\n';
  });
  throw new CommandResult({
    msg: result
  });
};

GitEngine.prototype.printRemotes = function(options) {
  var result = '';
  if (options.verbose) {
    result += 'origin (fetch)\n';

View on GitHub (pinned to 5b09d0ff96)

Solutions

1. Catch CommandResult separately from GitError when driving GitEngine programmatically
2. Use CommandResult.prototype instanceof checks to distinguish output from failure
3. Rely on the built-in command pipeline rather than calling printBranches directly

Example fix

// before
engine.printBranches(branches); // throws
// after
try { engine.printBranches(branches); }
catch (e) { if (e instanceof CommandResult) display(e.msg); else throw e; }

function isCommandResult(e){ return e instanceof CommandResult; }

try { engine.printBranches(branches); } catch (e) { if (e instanceof CommandResult) { show(e.msg); } else { throw e; } }

When it happens

Trigger: Any `git branch` (or branch listing variant) executed successfully; the thrown CommandResult is caught by the command pipeline and displayed.

Common situations: Not applicable as an error; only relevant when writing code that calls GitEngine directly and doesn't expect the throw-for-output pattern.

Related errors

• <dynamic tag listing>
• <dynamic remote listing>
• ' + ref + ' is not a branch
• ' + ref + ' is not a remote branch
• ' + branchName + ' is not a branch!

AI-assisted analysis of pcottle/learnGitBranching@5b09d0ff96 (2026-08-27). Data as JSON: /api/errors/db76c17ffaca4953. Report an issue: GitHub.