No useful feedback on failure w/ package.json that has conflicts

[mike-north]

NOTE: this issue predates this project's rename to Volta.

Repro Instructions

Create a repo with this package.json

package.json

```json { "name": "ember-cli-document-title-northm", "version": "0.0.0-development", "description": "Adding document title functionality to your ember app", "keywords": [ "ember-addon" ], "homepage": "https://github.com/mike-north/ember-cli-document-title-northm", "bugs": { "url": "https://github.com/mike-north/ember-cli-document-title-northm/issues" }, "license": "MIT", "author": "Mike North (https://mike.works)", "main": "index.js", "directories": { "doc": "doc", "test": "tests" }, "repository": { "type": "git", "url": "https://github.com/mike-north/ember-cli-document-title-northm.git" }, "scripts": { "build": "ember build", "lint:js": "eslint .", "start": "ember serve", "test": "ember test", "travis-deploy-once": "travis-deploy-once", "semantic-release": "semantic-release" }, "dependencies": { "ember-cli-babel": "^6.6.0" }, "devDependencies": { "@commitlint/cli": "7.2.1", "@commitlint/config-conventional": "7.1.2", "@commitlint/travis-cli": "7.2.1", <<<<<<< HEAD "@mike-north/js-lib-renovate-config": "^1.0.0", "@mike-north/js-lib-semantic-release-config": "^1.0.1", "@types/ember": "^3.0.25", "@types/ember__test-helpers": "^0.7.6", "broccoli-asset-rev": "^2.7.0", "chai": "^4.1.2", "ember-cli": "^3.6.0-beta.1", "ember-cli-dependency-checker": "^3.0.0", "ember-cli-eslint": "^4.2.1", "ember-cli-htmlbars": "^2.0.1", "ember-cli-htmlbars-inline-precompile": "^1.0.0", "ember-cli-inject-live-reload": "^1.8.2", "ember-cli-qunit": "^4.3.2", "ember-cli-shims": "^1.2.0", "ember-cli-sri": "^2.1.1", "ember-cli-uglify": "^2.0.0", "ember-disable-prototype-extensions": "^1.1.2", "ember-export-application-global": "^2.0.0", "ember-fastboot-addon-tests": "^0.4.0", "ember-load-initializers": "^1.1.0", "ember-maybe-import-regenerator": "^0.1.6", "ember-resolver": "^4.0.0", "ember-source": "~3.3.0", "ember-source-channel-url": "^1.0.1", "ember-try": "^1.1.0", "eslint-plugin-ember": "^5.0.0", "eslint-plugin-node": "^6.0.1", "husky": "^1.2.0", "loader.js": "^4.2.3", "qunit-dom": "^0.6.2", "travis-deploy-once": "^5.0.9" ======= "@mike-north/js-lib-renovate-config": "1.0.0", "@mike-north/js-lib-semantic-release-config": "1.0.1", "broccoli-asset-rev": "2.7.0", "chai": "4.2.0", "ember-cli": "3.6.0-beta.1", "ember-cli-dependency-checker": "3.0.0", "ember-cli-eslint": "4.2.3", "ember-cli-htmlbars": "2.0.5", "ember-cli-htmlbars-inline-precompile": "1.0.5", "ember-cli-inject-live-reload": "1.10.2", "ember-cli-qunit": "4.4.0", "ember-cli-shims": "1.2.0", "ember-cli-sri": "2.1.1", "ember-cli-uglify": "2.1.0", "ember-disable-prototype-extensions": "1.1.3", "ember-export-application-global": "2.0.0", "ember-fastboot-addon-tests": "0.5.0", "ember-load-initializers": "1.1.0", "ember-maybe-import-regenerator": "0.1.6", "ember-resolver": "4.5.6", "ember-source": "3.5.1", "ember-source-channel-url": "1.1.0", "ember-try": "1.1.0", "eslint-plugin-ember": "5.4.0", "eslint-plugin-node": "6.0.1", "husky": "1.2.0", "loader.js": "4.7.0", "qunit-dom": "0.8.1", "travis-deploy-once": "5.0.9" >>>>>>> 1b0732bc6d56cd3e87c32220760a687341129660 }, "engines": { "node": "6.* || 8.* || >= 10.*" }, "ember-addon": { "configPath": "tests/dummy/config" }, "commitlint": { "extends": [ "@commitlint/config-conventional" ] }, "husky": { "hooks": { "commit-msg": "./node_modules/.bin/commitlint -e $HUSKY_GIT_PARAMS" } }, "release": { "extends": "@mike-north/js-lib-semantic-release-config" }, "toolchain": { "node": "8.11.4", "yarn": "1.9.2" } } ```

and then attempt to run yarn

The error

Notion error: an internal error occurred

details: NotionError { error: ErrorImpl { code: KeyMustBeAString, line: 38, column: 1 }, user_friendly: false, exit_code: UnknownError }

stack backtrace:
   0:        0x10fa807ee - backtrace::backtrace::trace::hfab6a7185938ac36
   1:        0x10fa80c9c - backtrace::capture::Backtrace::new_unresolved::ha79782baa461e437
   2:        0x10fa7fcbd - failure::backtrace::internal::InternalBacktrace::new::hbcb9739880567208
   3:        0x10fa7feb4 - _$LT$failure..backtrace..Backtrace$u20$as$u20$core..default..Default$GT$::default::h65a4b2a10e0d004f
   4:        0x10fa7ff2d - failure::backtrace::Backtrace::new::he387e9ad94c85896
   5:        0x10f9c77e3 - _$LT$core..result..Result$LT$T$C$$u20$E$GT$$u20$as$u20$notion_fail..ResultExt$LT$T$C$$u20$E$GT$$GT$::unknown::hdfbc234154842748
   6:        0x10f973ae4 - notion_core::manifest::Manifest::for_dir::he015dccbe7534fea
   7:        0x10f974085 - notion_core::project::Project::for_dir::h5660b22e7bfd788b
   8:        0x10f973f1e - notion_core::project::Project::for_current_dir::h79f6cbc9980498e8
   9:        0x10f9c9a84 - notion_core::session::Session::new::h218b3e8a51ab2886
  10:        0x10f9458ab - notion_core::tool::Tool::launch::ha629c9c74094e603
  11:        0x10f945238 - yarn::main::hacc86d452ac61ed0
  12:        0x10f945205 - std::rt::lang_start::_$u7b$$u7b$closure$u7d$$u7d$::h1433e35cefe112a7
  13:        0x10fbf7b97 - std::panicking::try::do_call::h90c8830c237e1486 (.llvm.8493183658544739721)
  14:        0x10fc0430e - __rust_maybe_catch_panic
  15:        0x10fbe84fc - std::rt::lang_start_internal::h15876038f4767761
  16:        0x10f94526b - main

As a user, I'd want some information about my package.json being non-json or otherwise malformed -- maybe even providing an indication of where the problem exists in the json file.

[mike-north]

Related information about detecting merge conflicts: https://github.com/rust-lang/rust/issues/36879

[rwjblue]

Just to save additional searching, https://github.com/rust-lang/rust/issues/32059 is another issue related to this.

[chriskrycho]

One possible strategy for solving this: when we detect a parse failure when trying to read package.json, check it for conflict markers with a straightforward regex match on the string contents of the package.json file and report a more specific error type if so; otherwise, return the original error type.