[Breaking] ignore SyntaxErrors from readPackage/readPackageSync, eg due to a malformed package.json

This isn't really breaking, but I'm going to treat it as such, out of an abundance of caution.

Author: ljharb

lib/async.js

@@ -50,7 +50,7 @@ var defaultReadPackage = function defaultReadPackage(readFile, pkgfile, cb) {
                 var pkg = JSON.parse(body);
                 cb(null, pkg);
             } catch (jsonErr) {
-                cb(null);
+                cb(jsonErr);
             }
         }
     });
@@ -233,7 +233,7 @@ module.exports = function resolve(x, options, callback) {
                 if (!ex) return loadpkg(path.dirname(dir), cb);
 
                 readPackage(readFile, pkgfile, function (err, pkgParam) {
-                    if (err) cb(err);
+                    if (err && !(err instanceof SyntaxError)) cb(err);
 
                     var pkg = pkgParam;
 

lib/sync.js

@@ -46,11 +46,7 @@ var maybeRealpathSync = function maybeRealpathSync(realpathSync, x, opts) {
 };
 
 var defaultReadPackageSync = function defaultReadPackageSync(readFileSync, pkgfile) {
-    var body = readFileSync(pkgfile);
-    try {
-        var pkg = JSON.parse(body);
-        return pkg;
-    } catch (jsonErr) {}
+    return JSON.parse(readFileSync(pkgfile));
 };
 
 var getPackageCandidates = function getPackageCandidates(x, start, opts) {
@@ -145,7 +141,14 @@ module.exports = function resolveSync(x, options) {
             return loadpkg(path.dirname(dir));
         }
 
-        var pkg = readPackageSync(readFileSync, pkgfile);
+        var pkg;
+        try {
+            pkg = readPackageSync(readFileSync, pkgfile);
+        } catch (e) {
+            if (!(e instanceof SyntaxError)) {
+                throw e;
+            }
+        }
 
         if (pkg && opts.packageFilter) {
             pkg = opts.packageFilter(pkg, pkgfile, dir);

readme.markdown

@@ -78,7 +78,7 @@ options are:
 * `opts.readPackage(readFile, pkgfile, cb)` - function to asynchronously read and parse a package.json file
   * readFile - the passed `opts.readFile` or `fs.readFile` if not specified
   * pkgfile - path to package.json
-  * cb - callback
+  * cb - callback. a SyntaxError error argument will be ignored, all other error arguments will be treated as an error.
 
 * `opts.packageFilter(pkg, pkgfile, dir)` - transform the parsed package.json contents before looking at the "main" field
   * pkg - package data
@@ -152,7 +152,7 @@ default `opts` values:
                     var pkg = JSON.parse(body);
                     cb(null, pkg);
                 } catch (jsonErr) {
-                    cb(null);
+                    cb(jsonErr);
                 }
             }
         });
@@ -183,7 +183,7 @@ options are:
 
 * opts.realpathSync - function to synchronously resolve a potential symlink to its real path
 
-* `opts.readPackageSync(readFileSync, pkgfile)` - function to synchronously read and parse a package.json file
+* `opts.readPackageSync(readFileSync, pkgfile)` - function to synchronously read and parse a package.json file. a thrown SyntaxError will be ignored, all other exceptions will propagate.
   * readFileSync - the passed `opts.readFileSync` or `fs.readFileSync` if not specified
   * pkgfile - path to package.json
 
@@ -256,11 +256,7 @@ default `opts` values:
         return file;
     },
     readPackageSync: function defaultReadPackageSync(readFileSync, pkgfile) {
-        var body = readFileSync(pkgfile);
-        try {
-            var pkg = JSON.parse(body);
-            return pkg;
-        } catch (jsonErr) {}
+        return JSON.parse(readFileSync(pkgfile));
     },
     moduleDirectory: 'node_modules',
     preserveSymlinks: false

test/resolver.js

@@ -572,7 +572,7 @@ test('malformed package.json', function (t) {
                         cb(null, JSON.parse(result));
                     } catch (e) {
                         t.ok(e instanceof SyntaxError, 'readPackage: malformed package.json parses as a syntax error');
-                        cb(null);
+                        cb(e);
                     }
                 });
             }

test/resolver_sync.js

@@ -424,6 +424,7 @@ test('malformed package.json', function (t) {
                     return JSON.parse(result);
                 } catch (e) {
                     t.ok(e instanceof SyntaxError, 'readPackageSync: malformed package.json parses as a syntax error');
+                    throw e;
                 }
             }
         }