Throw objects not strings

$ grep -i throw.*tojson\( src/mongo/shell/*.js

src/mongo/shell/collection.js:        throw "error " + tojson( ret );

src/mongo/shell/collection.js:    throw "error dropping indexes : " + tojson( res );

src/mongo/shell/collection.js:        throw "drop failed: " + tojson( ret );

src/mongo/shell/collection.js:        throw "findAndModifyFailed failed: " + tojson( ret );

src/mongo/shell/collection.js:        throw "distinct failed: " + tojson( res );

src/mongo/shell/collection.js:        throw "distinct failed: " + tojson( res );

src/mongo/shell/collection.js:        throw "aggregate failed: " + tojson(res);

src/mongo/shell/collection.js:        throw "map reduce failed:" + tojson(raw);

src/mongo/shell/db.js:            throw "Could not insert into system.users: " + tojson(e);

src/mongo/shell/db.js:        throw "profile command failed: " + tojson( res );

src/mongo/shell/db.js:          throw tojson( res );

src/mongo/shell/db.js:        throw "group command failed: " + tojson( ret );

src/mongo/shell/db.js:        throw "getlasterror failed: " + tojson( res );

src/mongo/shell/db.js:        throw "getlasterror failed: " + tojson( res );

src/mongo/shell/mongo.js:        throw "listDatabases failed:" + tojson( res );

src/mongo/shell/query.js:        throw "error: " + tojson( ret );

src/mongo/shell/query.js:        throw "error: " + tojson( ret );

src/mongo/shell/query.js:    throw "count failed: " + tojson( res );

src/mongo/shell/query.js:            throw "error: " + tojson( ret );

src/mongo/shell/shardingtest.js:    throw "command " + tojson( cmd ) + " failed: " + tojson( res );